Pressure Boosting

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KSB Know-how, Volume 5

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Planning information for pressure boosting

November 2007 edition

Subject to technical modifications.

KSB Aktiengesellschaft Division:

Building Services Pumps D-91253 Pegnitz

All rights concerning public distribution through film, radio, television, video, photo-mechanical reproduction, sound and data storage devices of any kind, the printing of excerpts, and the saving, accessing and manipulation of data in any way, shape or form are only granted with the expressed permission of the manufacturer.

KSB – the complete range!

Pumps and systems for pressure boosting and fire fighting

Hya-Solo E

Hya-Solo D/DV

Hya-Eco K/VP

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Contents

Page

1 Foreword 3

2 Fundamentals 4

3 Calculating the hydraulic data of pressure boosting units 8

3.1 Calculating the flow rate of a pressure boosting unit 8

3.1.1 Calculation example (1) – Drinking water supply system for a residential building

3.2 Calculating the pressure values and pressure zones 9

3.2.1 Connection types 9

3.2.2 Calculating the available pressure upstream of the PBU (p_inl) 9

3.2.2.1 Determining the pressure zone upstream of the PBU 9

3.2.2.2 Calculation example for direct connection; continuation of (1) 10

3.2.3 Calculating the required pressure downstream of the PBU (pdischarge) 12

3.2.4 Calculating the discharge head of the PBU 13

3.2.5 Determining the pressure zone(s) downstream of the PBU 13

4 Calculation example (2) – Calculating the hydraulic data of a PBU for the supply of 14 fire-fighting water for wall-mounted fire hydrants

5 Choosing the correct PBU variant (Pump type) – with calculation examples (3) + (4) 15

5.1 PBU with cascade control (Hya-Eco and Hyamat K) 15

5.2 PBU with one variable speed pump (Hyamat V) 20

5.3 PBU with speed control on all pumps (Hyamat VP) 26

6 Overview – Connection types for drinking water and service water installations 28

7 Overview – Connection types for fire-fighting systems, wet risers 30

8 Overview – Connection types for combined installations 32

(drinking and fire-fighting water supply as well as service and fire-fighting water supply)

9 Overview – Connection types for wet- / dry-type systems 33

10 Accumulator selection / calculations 34

11 Dry running protection, selection criteria for PBUs 37

11.1 Protection of the supply network 37

11.2 Protection of pressure boosting unit 37

12 Effects of inlet pressure fluctuations 39

12.1 Indirect connection 39

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Contents

Page

13 Causes of pressure surges 42

13.1 Pressure surges caused by valves 42

13.2 Pressure surges as a result of inlet pressure fluctuations 42

14 Standards, directives and statutory regulations 43

15 Inspection, maintenance and repair 46

16 Nomenclature 47

17 References 50

18 Annex

Worksheet 1, Calculation flow rates and minimum flow pressures 52

Worksheet 2, Calculating the peak flow rate 53

Worksheet 3, Flow rates 54

Worksheet 4, Water meters 55

Worksheet 5, Filters, drinking water heating systems, pressure losses in consumer supply pipes 56

Worksheet 6, Conversion of discharge head H into pressure increase ⌬p 57

Worksheet 7, Head losses of steel pipes 58

Worksheet 8, Head losses of low-friction pipes 59

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1

Foreword

This brochure is intended for all involved with the planning, design and service of pressure boosting units (PBU).

Pressure boosting units are often found in modern office, residential and hotel buildings for general water provision and fire-fighting purposes. Considering the various PBU design concepts such as

• cascade control (Hya-Eco, Hyamat K)

• variable-speed control for one pump (Hyamat V)

• variable-speed control for all pumps (Hyamat VP)

• etc.

it is particularly important to select the right PBU concept for the specific project at the planning stage.

This brochure offers design guidance for pressure boosting units ensuring easy installation and uninterrupted water supply.

KSB justifies its status as a full-line supplier of pumps for building services by constantly devel-oping its range of products according to the requirements of its customers.

Pressure boosting units have the following typical applications: • Residential buildings • Office buildings • Hotels • Department stores • Clinics/hospitals

• Trade and industry plants

• Spray and conventional irrigation • Rainwater harvesting

• Small-scale domestic water supply units A pressure boosting unit is required when the minimum pressure supplied by the local water provider, see Fig. 1, is insufficient.

Pressure boosting units and their ancillary com-ponents must be designed and operated in such a way that neither the public water supply nor any other consumer units are interfered with – any degradation in the quality of drinking water must likewise be ruled out.

The regulations referred to in the brochure are based upon regulations in force in Germany at the time of writing. To ensure compliance, reference should be made to LOCAL and current regula-tions.

1

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2

Fundamentals

Drinking water is a consumable product, and is therefore subject to strict legal regulations. The essential requirements for drinking water quality are laid down in:

DIN 2000

Central drinking water supply DIN 2001

Drinking water supply from small units and non-stationary plants

IfSG

Protection Against Infection Act LMBG

Foodstuffs and Commodities Act TrinkwV

Drinking Water Ordinance

The regulations for adequate water provision to consumers which are applicable to units situated in buildings and property are as follows:

AVB Wasser V

General Water Supply Terms Ordinance DIN 1988

Drinking water supply units

DIN EN 805

Water supply – Requirements for units and components outside buildings (if agreed upon) DIN EN 806

Specifications for installations inside buildings conveying water for human consumption (if agreed upon)

(Public drinking water supply, for which KSB also offers an extensive pump programme, is not dealt with here.)

In terms of the origins of drinking water, a differ-ence must be made between centralized and/or local individual water supply units.

The following discussion deals with both possible applications.

In all cases where the minimum supplied water pressure (p_min,V) does not enable an unconditional supply to all extraction points, i.e.:

p_min,V<∆p_geo+ p_min,flow+ Σ(R · l+ Z) + [1] ∆pwm+ ∆pap [bar]

the deployment of a PBU is necessary. Legend for [1]:

pmin,V = Minimum pressure available at the

local water provider’s hand-over point ∆pgeo = Static pressure loss

pmin,flow= Minimum flow pressure at the least hydraulically favourable extraction point

2

Fundamentals

Fig. 1:

000

Mains water supply pipe

Service pipe Installation within the building Water meter Consumer supply pipe upstream of the PBU Consumer supply pipe upstream of the PBU PBU= Pressure boosting unit and

ancillary components PBU

Hand-over point-local water provider (public/private)

m3

Fil

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Σ(R·l+Z) = Pipe friction and other losses ∆pwm = Water meter pressure loss ∆pap = Apparatus pressure loss

The configuration and function of the PBU are de-scribed in DIN 1988 Part 5. This standard applies to centralized and individual water provision units. It prescribes, amongst other things, built-in stand-by pumps suitable for immediate operation for the transportation of drinking water. Perman-ent operating reliability is required according to DIN EN 806 Part 2.

Omitting the installation of a stand-by pump alongside a PBU for drinking water supply may be justified when the breakdown of a PBU does not seriously affect residents’ requirements, e.g. in the case of weekend houses. Here, a PBU may be in-stalled and operated without a stand-by pump. Permission must however always be sought from the responsible Water Authority.

As a rule, the integration of the PBU (Fig. 1) must be performed in such a way that adverse hydraulic effects on the public water supply network are minimized. This is facilitated through the selection of suitable components which in turn relies on knowledge of inlet pressure fluctuation and the maximum connection capacity of the service pipe together with an examination of the flow velocity in the house service pipe.

Anti-vibration mounting of the PBU (e.g. expan-sion joints with length limiters, anti-vibration mounts) markedly contributes to a reduction in solid-borne sound transmission.

Fluctuating inlet pressures

Fluctuations in the supply pressure have a consid-erable effect on the operating characteristics of the PBU.

These range from a dramatic rise in switching frequency (excessive on/off) to increased levels of discharge pressure fluctuation. In certain cases, the rated pressure of the unit components can be exceeded. This leads in all cases to pressure surges and consequent wear on all associated parts.

If the inlet pressure fluctuations lie beyond +0.3/-0.2 bar, the following remedial action is possible and may be necessary:

• Pressure controller / reducer upstream of the PBU (type series Hyamat K, Hyamat V, Hya-Eco) • PBUs with variable speed base load pump

(type series Hyamat V) (see also section 5.5.2) • for large inlet pressure fluctuations: PBUs with

speed control on all pumps (type series Hyamat VP)

Distribution of flow volume

Decisive for sizing the individual pumps of a PBU is the relationship between the PBU’s design flow rate and the maximum connection capacity of the service pipe. Particularly in the case of PBUs with cascade control (Hya-Eco and Hyamat K range) it is important to ensure that the velocity change in the service pipe does not exceed 0.15m/s when the individual pumps are started and stopped. This can be achieved by distributing the design flow rate across several pumps.

Possible remedies:

• Incorporating membrane-type accumulators on the inlet side

• Indirect connection via unpressurized inlet tank • PBU with one variable speed base load pump

(Hyamat V)

• PBU with speed control on all pumps (Hyamat VP)

Demand fluctuations

Sudden changes in demand downstream of a PBU can lead to pressure surges/noises in the discharge-side distribution unit.

Pressure surges can sometimes trigger safety devices or even cause damage to apparatus or lead to burst pipes and increased wear on pumps, valves, and piping. Reduction in the highly dynamic levels of consumption is the most effective

2

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remedy (e.g. through the replacement of solenoid valves with motor-operated valves).

Just as important is the adequate sizing of the pump in relation to its nominal flow rate.

∆Q_Pu> ∆Q_max,dyn [m3_/h] _[2]

Legend for [2]:

∆Qmax,dyn= Change of flow of a highly dynamic

consumer

∆QPu = Change of flow rate of each pump In addition, membrane-type accumulators fitted directly upstream of dynamic consumers reduce the aforementioned effects. These must be of the direct-flow type.

PBUs incorporating continuously variable speed control on all pumps (Hyamat VP) can respond better to high consumer fluctuations due to the synchronized operating mode of the pumps.

Noises

Modern PBUs are expected to operate with a minimum of noise.

Operating noise (airborne sound) is mainly gener-ated by the electric motor fans.

Cladding can considerably reduce noise emission. The selection of an appropriate location is likewise an important factor (away from recreation rooms and bedrooms).

In operation, pumps create vibrations, flow noise and solid-borne noise. The provision of adequate sound insulation of the piping from the PBU is therefore of primary importance, and every PBU must be separated from the piping and structure surrounding it by suitable sound insulation (i.e. expansion joints with length limiters, anti-vibra-tion mounting using rubber-bonded metal elements).

Expansion joints must be easily replaceable. With regard to flow noises, a moderate flow vel-ocity in piping, apparatus and pipe fittings should be ensured.

Hygiene

In view of hygiene requirements, a distinction should be made between units dealing with drink-ing water and those handldrink-ing service water. Drinking water:

According to the Drinking Water Ordinance (ex-cerpt) drinking water is referred to as “water for human consumption and use”. Drinking water is to be understood as water in its original condition or after treatment which is used for drinking, cooking, preparing meals and beverages, for per-sonal hygiene and the cleaning of objects which are destined to be used with food and those which are temporarily in contact with the human body. Service water:

“Water to serve commercial, industrial, agricul-tural or similar purposes with varying levels of quality which can include drinking water”. When operating a PBU it is important that water quality is not impaired.

An essential requirement is: operation of the PBU and its associated components should not allow stagnation.

As a closed unit rules out any health risk resulting from external contamination of drinking water, units with direct connection should be preferred to those with indirect connection.

The following measures reduce the chance of water stagnating:

• Direct-flow membrane-type accumulators (dual connection)

• Automatic switchover between all pumps • Smallest possible dead spaces in components

handling water

• Forced flushing of pipe sections where stagnation could occur

A further aspect of hygiene is the temperature of the fluid.

The following factors can lead to a temperature increase of the water inside PBU components – unpressurized inlet tank, pumps, pipe components and membrane-type accumulators:

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• Increased ambient temperature at the site of installation

• Long periods of minimum consumption (office buildings at the weekend)

• Temperature increase due to the pumping operation (heat losses).

These factors can be eliminated through the selec-tion of an appropriate locaselec-tion and the prompt stopping of pumps at minimum/zero consumption. The materials and auxiliary equipment used in the construction of a PBU must be in line with the relevant regulations regarding the compatibility with drinking water (as stipulated, for example, by the German LMBG, KTW, DVGW regulations). Cleanliness during construction, transport, instal-lation and commissioning of a PBU und its associ-ated equipment, together with a final flushing of the entire unit according to DIN 1988 Part 2 or ZVSHK technical instruction leaflet, are manda-tory requirements for water according to DIN 2000 which is:

• Absolutely hygienic • Cool

• Neutral in terms of taste and odour • Clear

• Free from foreign substances

2

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3

Calculating the hydraulic data of pressure boosting units

3.1

Calculating the flow rate of a pressure boosting unit

3.1.1

Calculation example (1)

Drinking water supply system for a residential building

The calculation is performed on the basis of DIN 1988 (1988 edition).

The assumptions are as follows:

High-rise residential building with basement, ground floor and a further 14 floors, see Fig. 4. 97 identically equipped living units have to be supplied with drinking water. The living units (LU) are equipped as follows:

Per living unit (LU):

2 toilets with cisterns, DN 15 1 bath tub, DN 15 1 shower, DN 15 2 sink units, DN 15 1 bidet, DN 15 1 washing machine, DN 15 1 dishwasher, DN 15 1 kitchen sink, DN 15

The required total flow ΣV·Rshould as a rule be established on the basis of the specifications made by the taps, showerheads and fittings manufactur-ers.

If in a specific case such information is not avail-able, the total flow can be calculated by means of Worksheet No. 1 in the Appendix.

According to this Worksheet ΣV·Ris as follows: Appliance flow rates

2 toilets 0.26 l/s 1 bath tub 0.3 l/s 1 shower 0.3 l/s 2 sink units 0.28 l/s 1 bidet 0.14 l/s 1 washing machine 0.25 l/s 1 dishwasher 0.15 l/s 1 kitchen sink 0.14 l/s

This gives a required total flow per living unit of: 1.82 l/s

The total calculated flow for 97 living units is: ΣV·cal = 97 · 1.82 l/s = 176.5 l/s

In practice, total flow is never required.

For the determination of a realistic peak flow V·peak use Worksheet 2, curve A, in the Appendix.

3

Calculating the flow rate of the PBU

Flow rate in m3/h (l/s)

Drinking water demand 4 5 6 8 9 10 11 12 13 14 15 20 25 30 40 50

(1.11) (1.39) 1.67 2.22 (2.5) 2.78 3.06 3.33 3.61 3.89 4.17 5.56 6.94 8.33 11.1 13.9 Residential buildings 1) 4 6 10 30 45 60 75 95 115 140 180 up to ... living units Hospital 2) 30 40 50 65 75 85 95 100 115 125 135 180 230 300 420 560 up to ... beds Office buildings 2) 160 200 240 340 380 440 480 540 600 660 730 1100 1500 2000 up to ... employees Hotel2) 20 25 30 40 45 50 55 60 65 70 75 100 125 155 210 280 up to ... beds Department store 2) 40 50 60 85 95 105 115 125 135 150 160 220 300 400 750 1400 up to ... employees

1) _{These are reference values for living units with standard equipment (V}·

cal< 1 l/s); for living units with more “luxury” installations higher values must be considered and/or a detailed calculation performed.

2) These reference values serve merely as a guideline. To determine the water consumption, the design engineer has to calculate the expected max. consumption taking the installations and their usage into account.

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3

The resultant peak flow is: V·_peak = 4.4 l/s

The PBU to be selected must be capable of handling at least this peak flow.The following equation is therefore applied:

V·_peak =^ V_max,P =^ Q_D = 4.4 l/s 앒 15.9 m3_/h

In pumping technology, the peak flow (V·_peak) corresponds to the design flow rate of the PBU (QD).

For an approximate calculation of the flow rate, below table 1 can be used.

3.2

Calculating the pressure values and pressure zones

3.2.1

Connection types

As a rule, a distinction is made between the direct and indirect connection of a PBU to the water supply unit.

The water provider will determine the type of connection permitted.

3.2.1.1

Direct connection of a PBU, Fig. 2

This type of connection is characterized by a spe-cific inlet pressure (pinl) available upstream of the PBU.

As the supply pressure level at the hand-over point can vary between p_min,V and p_max,V, the resultant inlet pressure p_inlupstream of the PBU has to be established according to the example in section 3.2.2.2.

3.2.1.2

Indirect connection of a PBU, Fig. 3

As the unit is separated through the installation of an unpressurized inlet tank (indirect connection type), the existing supply pressure is reduced to the ambient pressure; hence installing the PBU on the same level as the inlet tank means that only the filling level of the inlet tank is the available hydro-static inlet pressure (p_inl앒 0.1 bar).

Hence, an inlet pressure (pinl) of 0 bar is assumed

for the design of the PBU. N.B.

If the installation level of the unpressurized inlet tank is lower than that of the PBU, the PBU must be designed for suction lift operation.

3.2.2

Calculating the available pressure upstream of the PBU (p_inl)

3.2.2.1

Determining the pressure zone upstream of the PBU

The number of floors can be established through the following equation:

Fig. 2:

Flow diagram, direct connection of a pressure boosting unit (PBU)

0 0 0

Mains water supply pipe p max,V p min,V _p inlet PBU m 3 Fil Water meter

Service pipe Consumer pipes upstream of the PBU

Consumer pipes downstream of the PBU

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pinl, min– pflow– ∆pdyn NwithoutPBU울 ––––––—––––––––– [3] ∆pfl 2.47 – 1.0 – 0.2 NwithoutPBU울 ––––—–––––––_0.3 NwithoutPBU= 4.23 Rounded down N_{without PBU} = 4

Counting from the branch (upstream of the PBU inlet pipe), the first 4 floors (ground floor, 1st, 2nd and 3rd floor) can be supplied directly, Fig. 4.

Water supply by means of a PBU is required from the 4th floor, Fig. 4.

Legend for [3]:

N_{without PBU}= Number of floors which can be supplied without PBU

pinl,min = Minimum pressure

available upstream of the PBU

p_flow = Flow pressure at consumer ⌬pdyn = Dynamic pressure difference ⌬pfl = Pressure loss per floor

3.2.2.2

Calculation example for direct connection; continuation of (1)

The local water provider provides the following information for a drinking water installation as per section 3.1.1:

p_min,V = 2.8 bar

pmax,V = 4.8 bar

Nom. diameter of service pipe: DN 80 Direct connection of PBU

Woltmann-type water meter

3

Fig. 4: pressure zone, here pressure reduction measures are not required Basement Ground floor 5th 4th 3rd 2nd 1st 15th . . . . . . . . . . N without PBU= 4 N flpr = 6 PBU 000 pmax,V pmin,V pinlet 0 bar PBU

Mains water supply pipe

Water meter

Consumer pipes downstream

of the PBU

Hand-over point (local water provider) m3

Fil

Fig. 3:

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Calculation of minimum, maximum and inlet pressure fluctuations upstream of the PBU. Σ(R·l+Z)inl = 0.1 bar

(assumption made by engineering consultant)

V·peak ⌬pwm =

[

–––––

]

2 · ⌬p V·_max 15.9 1 ⌬pwm =

[

–––––

]

2 · 600 · ––––– bar 30 1000 = 0.17 bar

(Woltmann-type water meter, vertical, DN 50, see Worksheet 4, Appendix)

V·S ⌬pap =

[

–––––

]

2 · ⌬p V·_max 15.9 1 ⌬pap =

[

–––––

]

2 · 200 ·––––– bar 30 1000 = 0.06 bar

(Filter: nom. throughflow 30 m3_{/h, see} Work-sheet 5, Appendix)

Minimum pressure:

This level is reached under min. supply pressure

p_min,Vand simultaneous max. water consumption

V·_peakconditions. This requires that the dynamic pressure losses in the installation between hand-over point (local water provider) and PBU inlet be taken into account.

[4] Result, Fig. 5: p_inl,min = 2.8 – 0.1 – 0.17 – 0.06 = 2.47 bar pinl,min 앒 2.5 bar p_inl,max = 4.8 bar ⌬pinl = 4.8 – 2.5 = 2.3 bar

The PBU must be able to operate reliably with an inlet pressure fluctuation of ⌬pinl= 2.3 bar. The inlet pressure pinlupstream of the PBU fluctuates to a greater extent than the supply pressure at the hand-over point. Therefore, it must be possible to operate the PBU with a supply pres-sure fluctuation ⌬pinl. This must be examined for each specific unit and, if necessary, appropriate measures should be taken to properly protect the unit (e.g. pressure reducers).

Maximum pressure:

This level is reached under maximum supply pressure p_max,V and simultaneous minimum water consumption conditions. The dynamic pressure losses in the supply-side installation can be dis-regarded.

[5] pinl,max = pmax,V [bar]

p_inl,min = p_min,V– Σ(R · l + Z)_inl– ∆p_wm– ∆pap [bar]

3

Fig. 5:

Flow diagram, direct connection of PBU including pressure values

0 0 0 p max,v = 4.8 bar = 2.8 bar p min,v p inl,min p inl,max = 2.5 bar = 4.8 bar PBU m 3 Fil Water meter Mains water supply

pipe

Consumer pipes downstream of the PBU

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[6]

Legend for [4], [5], [6]:

p_inl,min = Minimum available pressure upstream

of the PBU

pmin,V = Minimum available pressure at the local

water provider’s hand-over point Σ(R·l+Z)inl = Pipe friction and other losses from

the supply pipe to the PBU ⌬pwm = Water meter pressure loss ⌬pap = Apparatus pressure loss

pinl,max = Maximum pressure upstream of the PBU

p_max,V = Maximum available pressure at the local

water provider’s hand-over point ⌬pinl = Pressure fluctuation upstream of the PBU

3.2.3

Calculating the required pressure downstream of the PBU (p_discharge)

Calculation example:

The residential building as per section 3.1.1 is provided with 97 identical living units. All floors – basement, ground floor and a further 14 floors – have a floor height of 3 m.

[7]

Calculation procedure:

The static head loss is calculated on the basis of the number of floors (N) and the floor height (Hfl).

[8]

3

*) Whether this approach is hydraulically permissi-ble must, however, be checked by means of the KSB documentation.

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4

Supply of fire-fighting water for wall-mounted fire hydrants 4

Calculation example (2):

Calculating the hydraulic data of a PBU for the supply of fire-fighting water for wall-mounted fire hydrants

The residential building as per section 3.1.1 is equipped with 18 fire hydrants including standard fire service connections which must be supplied with fire-fighting water by a PBU.

The peak flow (V·peak) for the fire-fighting water supply is calculated exclusively on the basis of the calculated flow rate per hydrant multiplied by the simultaneity factor (f).

The calculated flow per wall-mounted fire hydrant is V·_cal= 100 l/min = 6 m3_{/h (Worksheet 3,} Appen-dix) for a hydrant marked “F”. A simultaneity factor of f = 3 according to DIN 14461 part 1 has been laid down.

In the example, the peak flow (V·peak) and therefore the design flow rate (QD) of the PBU for the supply of fire-fighting water is:

[11]

V·peak= 6 m3/h · 3 = 18 m3/h = QD Legend for [11]:

V·peak= Peak flow of a PBU

V·_cal = Calculated flow rate per hydrant f = Simultaneity factor

Q_D = Design flow rate of a PBU

According to EN 806-2: 2005 the following applies to PBUs for water supply and fire-fighting:

The flow rate of the PBU should be the high-er value of both supply requirements.

Calculating the pump discharge head H:

H = (pdischarge– pinl,min) · 10 [m] [12]

Using the discharge head calculation for drinking water, the discharge pressure and head of the fire-fighting PBU can be established with the following formula:

[13]

Legend for [13]:

⌬pgeo = Pressure loss from static head difference Σ(R·l+Z)discharge = Pipe friction and other losses

down-stream of the PBU

p_min,hydr = Minimum flow pressure at the least

hydraulically favourable hydrant

pinl,min = Minimum available pressure upstream

of the PBU

H = (4.5 + 1.05 + 3.0 – 1.8) m · 10 = 67.5 m

Selected: Hya-Solo D 1807 / 1.8

(1 Pump, 7.5 kW, p_co= 9.6 bar, p_ci= 11.6 bar, pressure-dependent control)

The standard applied for the pressure boosting units is DIN 1988-5 or, if agreed upon, DIN EN 806-2. In addition, the requirements for the respective fire-fighting concept are applicable.

∆pP = ∆pgeo+ Σ(R · l + Z)discharge+ pmin,hydr – pinl,min [bar]

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Choosing the correct PBU variant

5

Choosing the correct PBU variant (Pump type) – with calculation examples (3) + (4)

5.1

PBU with cascade control (Hya-Eco and Hyamat K) 5.1.1

Features

• Pumps are started / stopped as a function of pressure

• Pumps run at full speed • Auto-changeover of pumps • Output pressure fluctuates

by min. (pco– pci) by max. (p0– pci) + ⌬pinl

• Excessive on/off ("hunting") occurs when the water demand falls below a min. capacity Q_min(p_co)

• The range of excessive on/off operation is enlarged with increasing pinl(inlet pressure).

This is particularly noticeable in the case of pumps with fewer stages (flat pump curve) • In the case of inlet pressure fluctuations,

potential use of the inlet pressure is limited • Therefore, upstream pressure reducers are

frequently required

• Adverse hydraulic impact on the mains supply network is relatively high

5.1.2

Calculation example (3) Discharge head of PBU Calculating the required pressure downstream of the (pdischarge)

[14]

pdischarge = 3.3 + 1.1 + 1.0 (assumed values)

pdischarge = 5.4 bar

The discharge pressure(pdischarge) required of a PBU with cascade control is the cut-in pressure (pci). Depending on the design of the pump, the discharge pressure can rise up to the value p0= pinl+ H0/ 10.

This increase in pressure always depends on the type of pumps selected (flat/steep charac-teristic curve).

According to the local water provider, the supply pressure at the hand-over point may vary between a minimum value of

pmin,V = 2.2 bar and a maximum value of

pmax,V= 3.5 bar. As the inlet pressure fluctuations are too high for cascade control, it is necessary to install a pressure reducer. Due to the pressure reduction of approx. 0.7 bar achieved by the pressure reducer, the available inlet pressure is lowered to pinl= 1.5 bar.

p_discharge= ⌬p_geo+ Σ(R · l + Z) + p_min,flow [bar]

Hyamat K On/Off Cascade control pco p pci p(co-ci) Q Fig. 6:

Performance chart of a PBU with cascade control (type series: Hya-Eco and Hyamat K)

pco p0 pci p(co-ci) Fluctuation range of discharge pressure Q Qmin (p )co Excessive on/off H

5

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5

Choosing the correct PBU variant The pump’s discharge head is therefore established

as follows:

[15]

H = (5.4 – 1.5) · 10

H = 39 m (Fig. 7)

Legend for [14], [15]:

pdischarge= Required pressure downstream of the PBU ⌬pgeo = Static pressure loss

Σ(R·l+Z) = Pipe friction and other losses

pmin,flow= Minimum flow pressure at the consumer

pinl = Available inlet pressure upstream of the PBU

Selecting the appropriate PBU size(s): V·_peak = Q_D = 24 m3_/h

(assumed) H = 39 m

The following pumps have been selected

1. Hyamat K 5/0407/1.5 (5 pumps),

2. Hyamat K 6/0406/1.5 (6 pumps),

both options with stand-by pump

5.1.3

Determining the pressure zones Calculating p_minand p_maxper floor: (Refer to Fig. 8)

The max. discharge pressure

p_discharge= p₀= p_inl+ H₀/10 is assumed for the PBU’ discharge pressure (p_discharge).

We assume that the installation of an upstream pressure reducer for a PBU in cascade operation is always compulsory.

The available pressure upstream of the PBU (p_inl) is to be understood as the pressure reducer’s out-put pressure. If a pressure reducer has not been in-stalled, the max. possible supply pressure (p_max,V) is to be used for p_inl

[16]

8.0 – 5.0

Nflpr = ––––––––– = 10 0.3

Legend for [16]:

N_flpr = Number of floors which have to be protected against inad-missible pressures by means of pressure reducers

pdischarge= Required pressure downstream

of the PBU

p_max = Maximum permissible flow pressure at consumer

⌬pfl = Pressure loss per floor (hfl = 3m) H = (p_discharge– p_inl) · 10 [m]

Fig. 7: Performance chart of a PBU with cascade control including pressure values for a specifically chosen

pump with inlet pressure (p_inl)

p0 pco pci pinl = 8.0 = 7.7 = 5.4 39 65 6.0 4.5 3.0 = 1.5 50 30 20 10 0 Fluctuation range for p at constant inlet pressure discharge

Output pressure from the pressure reducer

Pressure increase of pump incl. inlet pressure pinl

Pump discharge head for pinl = 0 bar

Q Qmin (p )co QN H [m] pdischarge [bar] pdischarge– pmax N_flpr = –––––––––––––– ⌬pfl

(19)

5

Calculating the max. flow pressure on a random floor p_max,fl

Assumption:

Water consumption is zero or very low. Therefore, the head loss is H_L ≈ 0

Calculation:

The max. floor pressure (p_max,fl) is calculated by deducting the static pressure loss ⌬p_geo(floor X) of the respective floor from the PBU discharge pressure (p_discharge).

The static pressure loss of a building with N = 11 floors, meaning ground floor + 10 floors, amounts to:

[17]

Where ⌬p_geo,fl = 0.3 bar ⌬pgeo = 11 · 0.3 bar = 3.3 bar

[18]

For example for the 10th_floor pmax = 8.0 bar – 3.3 bar = 4.7 bar

In general, the following calculation applies to the max. floor pressure:

[19]

[20]

0 Pumps per PBU

without stand-by pump

with stand-by pump according to DIN 1988 1 2 4 6 8 10 12 2 3 4 5 6 / / 2 3 4 5 6 3 6 9 12 15 18 4 8 12 16 20 24 5 10 15 20 25 30 6 12 18 24 30 36 7 14 21 28 35 42 8 16 24 32 40 48 9 18 27 36 45 54 14.4 p bar A H m Q m /h3 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 0415 0413 0411 0409 0408 0407 0406 0405 0404 0403 0402 12.4 10.5 9.5 8.5 6.6 5.6 4.6 3.6 pP = 3.9 bar 2.6 1.7 0 7.5 0410

Characteristic curve values and tolerances to ISO 9906

Fig. 8:

Selection chart Movitec 4

∆p_geo= N · ∆p_geo,fl [bar]

pmax= pdischarge– ∆pgeo (floor X) = p₀– ∆p_{geo (floor X)}[bar]

p_discharge= p₀ [bar]

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5

Choosing the correct PBU variant Legend for [17], [18], [19], [20]

⌬pgeo = Pressure loss from static head difference ⌬pgeo,fl= Pressure loss from static head

difference per floor

p₀ = Maximum pump pressure at zero flow rate (Q = 0)

pmax = Maximum pressure ⌬pfl = Pressure loss per floor

⌬pgeo (floor X) = Static pressure loss for floor X

Calculating the minimum flow pressure on a random floor

Assunption:

1. The PBU discharge pressure (p_discharge) corresponds to the cut-in pressure p_ci. 2. Water consumption is max QN= V·peak. 3. The dynamic pressure losses Σ(R·I+Z)

correspond to the maximum value.

4. For simplification we assume a linear distribu-tion of the pressure loss across the individual floors. This applies both to the static and dynamic pressure loss.

Calculation:

The following applies to a building with 11 floors (N = 11):

⌬pgeo,fl = 0.3 bar per floor A dynamic pressure loss of Σ(R·l+Z) = 1.1 bar

gives a dynamic pressure loss per floor of

[21]

1.1

⌬pdyn, fl =–—––––– = 0.1 bar

11

The calculated total pressure loss per floor is

[22]

⌬pfl = 0.3 bar + 0.1 bar ⌬pfl = 0.4 bar

In general, the following applies to the flow pressure at a floor:

[23]

Legend for [21], [22], [23]

⌬pdyn,fl = Dynamic pressure loss per floor

Σ(R·l+Z) = Pipe and other losses

⌬pfl,tot = Total pressure loss per floor ⌬pgeo,fl = Static pressure loss per floor pmin,flow (N)= Minimum flow pressure at the

consumer on floor N

pdischarge = Required pressure downstream of the

PBU

Example:

Determining the available flow pressure for the 5th_floor:

N = 6 (ground floor + 5 floors) using the values as per Fig. 9 gives: pmin,flow (6) = 5.4 bar – 0.4 bar · 6 p_{min,flow (6)} = 3.0 bar

Σ(R·l+Z)

⌬pdyn, fl = –—––––– [bar]

N

⌬pfl,tot= ⌬pgeo,fl+ ⌬pdyn,fl [bar]

(21)

5

5.1.4

Pressure zone calculation for a building equipped with a PBU using cascade control (Hya-Eco and Hyamat K)

Outcome:

In the event of pump failure, consumers are not affected since appropriate measures (installation of pressure reducers on the inlet side, establishing pressure zones on the consumer side) have been taken.

• Inlet pressure reducer:

Required as the inlet side pressure fluctuations are too high for cascade operation.

As a result of the pressure loss inherent in the reducer (here = ⌬p 0.7 bar) the minimum available inlet pressure p_inldrops to 1.5 bar. The nominal discharge head required of the pumps is thereby increased by 7 m.

• Consumer-side pressure reducer

On floors 3 to 8, the max. permissible pressure p_max= 5 bar would be exceeded (Fig. 9). For this reason, these floors require protection from pressure reducers. The available pressures are then set to a uniform pressure of 1.3 bar.

5.1.5 Summary

The cascade-controlled PBU is favourably priced.

However, tackling this unit’s negative consequences (pressure fluctuations, excessive on/off operation, hydraulic impact on the water supply network…) requires the installation of various additional

components (pressure controller, membrane-type accumulator…).

Top pressure zone, directly supplied via PBU

Bottom pressure zone, directly supplied via supply pressure Middle pressure zone, supplied via PBU, protected by a pressure reducer per floor

Basement Ground floor 10th 9th 8th 7th 6th 5th 4th 3rd 2nd 1st Hyamat K p 0 p ci p inl = 8.0 bar ± 0 m + 3.0 m + 6.0 m + 9.0 m + 12.0 m + 15.0 m + 18.0 m + 21.0 m + 24.0 m + 27.0 m + 30.0 m + 33.0 m p max = 6.8 bar p max = 6.5 bar p max = 6.2 bar p max = 5.9 bar p max = 5.6 bar p max = 5.3 bar p max = 5.0 bar = 5.4 bar p = min 3.8 bar p = min 3.4 bar p = min 3.0 bar p = min 2.6 bar p = min 2.2 bar p = min 1.8 bar p = min 1.4 bar =1.5 bar = 2.2 bar 1.4 bar p = 1.0 min bar p = 1.0 min bar 1.8 bar = 3.5 bar 2.9 bar p max = 2.6 bar p max = 4.7 bar 3.2 bar 1.3 bar 1.3 bar 1.3 bar 1.3 bar 1.3 bar 1.3 bar W F p max,V p min,V Fig. 9:

Schematic drawing of a PBU operating with cascade control incl. pressure values and pressure zones

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5

Choosing the correct PBU variant 5.2

PBU with one variable speed pump (Hyamat V) 5.2.1

Features

• One variable speed base load pump • Peak load pumps cut in depending on the

pressure (⌬p-range)

• Peak load pumps run at full speed

• Pump change-over of variable speed base load pumps is possible

• Discharge pressure is largely constant

• Inlet pressure fluctuations can be compensated for

• In the event of a malfunction of the speed control, unit operates like a cascade

• Under low flow conditions, the base load pump is shut down irrespective of the inlet pressure

• Hydraulic impact on the water supply network is low

• Inlet side pressure reducer is normally not required

5.2.2

Calculation example (4) Discharge head of PBU

The discharge pressure p_dischargeis calculated as follows

[24]

pdischarge= 3.3 bar + 1.1 bar + 1.0 bar = 5.4 bar

Legend for [24]

⌬pgeo = Static pressure loss

Σ(R·l+Z) = Pipe friction and other losses

pmin,flow = Minimum flow pressure at consumer

The required discharge pressure (p_discharge) on pressure boosting units with one variable speed pump is also referred to as the cut-in pressure (p_ci).

Under normal operating conditions, the discharge pressure is almost constant.

When peak load pumps are started or stopped, the discharge pressure may slightly deviate from p_ci (e. g. ± 0.5 bar) for a short period of time.

Note:

In the event of a malfunction (speed control failure) the unit automatically changes over to cascade operation. As a pressure reducer is not normally installed in the case of a PBU with one variable speed pump, the discharge pressure can rise to a maximum value of

p = p = p +H / 10.

p_discharge= _⌬p_geo+ _{Σ(R·l+Z) + p}_{min, flow}[bar]

Fig. 10:

Performance chart of a PBU with one variable p 0 p ci Q Excessive on/off Almost constant discharge pressure H n pumps n -1 pumps Hyamat V On / Off continuously controlled pump change-over One pump with continuous speed control

p

const. pci

(23)

Possible remedial measures:

Option 1

One central pressure reducer on the discharge side of the PBU

Setting the pressure reducer to the output pressure p_pr= 6.2 bar ensures that the pressure reducer is fully open under normal operating conditions. Only in the event of a fault is the pressure thus limited to the value set (p_pr= 6.2 bar).

Option 2

A pressure-controlled by-pass valve between inlet and discharge side of the PBU with additional tem-perature monitoring.

The by-pass valve opens as soon as the set pres-sure is reached or exceeded (p_discharge욷 6.2 bar). If consumer demand is low, the excess flow is routed to the PBU inlet.

The installation of an additional temperature monitoring device in the by-pass (hygiene!) ensures the pump is shutdown in the event of a prolonged period of low water demand.

Calculating the discharge head of the PBU The supply pressure at the hand-over point varies between the minimum pmin,V= 2.2 bar and the maximum value pmax,V= 3.5 bar.

Pressure boosting units with one variable speed pump are capable of handling supply pressure fluctuations (see Fig. 13 and 14) thus eliminating the need for pressure reducers.

The discharge head is determined on the basis of the minimum supply pressure pmin,V.

The pump head is calculated as follows:

[25]

H = (5.4 bar - 2.2 bar) · 10

H = 32 m (i.e. 7 m less than Hyamat K)

Legend for [25]:

pinl,min= Minimum available pressure upstream

of the PBU

5

Fig. 11

Central pressure control (e.g. pressure reducer)

p 0 p ci p pr =9.1 bar = 5.4 bar = 6.2 bar PBU Hyamat V p ci p mon p discharge = 5.4 bar = 6.2 bar 6.2 bar PBU Hyamat V T max ≥ Fig. 12

Pressure control using a by-pass valve

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5

Fig. 14:

Performance chart of a PBU with one variable speed pump, incl. pressure values, for a specific pump

p 0 without protection with protection p E ppr valve= p p inl,min = 7.8 = 5.4 32 Rotational speed = 76 % Rotational speed = 100 % H = 56 0 = 6.2 = 2.2 60 50 40 20 10 0 Pressure increase of pump(s) incl. min. inlet pressure

p inl,min

Discharge head of pump(s) for

p = inl 0 bar

Discharge pressure Pump discharge head

Q Q N H [m]

p discharge [bar]

min. inlet pressure

Fig. 13:

Performance chart of a PBU with one variable speed pump, incl. pressure values for operation with max. inlet pressure p_inl,max. Inlet pressure reducers are not normally installed with this type of system!

The max. inlet pressure pinl,max, is

critical for calculating the max.

discharge pressure p0.

The max. discharge pressure p0can

only occur in the case of a fault in the continuous speed control. (Change-over to cascade operation). p 0 without protection with protection p ci p_{pr valve}= p p inl,max = 9.1 = 5.4 19 Rotational speed = 58 % Rotational speed = 100 % H = 56 0 = 6.2 = 3.5 60 50 40 30 10 0 Discharge pressure Pressure increase of pump(s) incl. max. inlet pressure

p inl,max

Discharge head of pump(s) for

p = inl 0 bar

Pump discharge head

Q Q N H [m]

p discharge [bar]

(25)

5

Selecting the appropriate PBU size(s): V·peak = QD = 24 m3/h (assumed)

H = 32 m

The pumps selected

1. Hyamat V 5/0406/2,2 (5 pumps) ⌬pinl,perm = 1.3 bar,

2. Hyamat V 6/0405/2,2 (6 pumps) ⌬pinl,perm = 1.5 bar,

with stand-by pump for each option

In this case (⌬p_inl= 1.3 bar) both PBU sizes can operate without a pressure reducer on the inlet pressure side.

Pumps per PBU

without stand-by pump

with stand-by pump according to DIN 1988 8 10 12 – – – 5 6 / / 5 6 12 15 18 16 20 24 20 25 30 24 30 36 28 35 42 0 0 0 0 0 0 0 0 0 0 0 0 Movitec 0415 Movitec 0413 Movitec 0411 Movitec 0410 Movitec 0409 Movitec 0408 Movitec 0407 Movitec 0406 Movitec 0405 Movitec 0404 Movitec 0403 Movitec 0402 32 40 48 36 45 54 14.4 p bar A H m Q m /h3 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 0415 0413 0411 0409 0408 0407 0406 0405 0404 0403 0402 12.4 10.5 9.5 8.5 6.6 5.6 4.6 3.6 p_P= 3 2. bar 2.6 1.7 0 7.5 0410

Characteristic curve values and tolerances to ISO 9906

– – – 1 1 1 1 1 1 1 1 1.3 1 1.5 1 1 1 2 2 2 2 2 2 2 2 2 2 1.5 3 3 3 3 3 3 3 3 3 4 4 4 4 4 4 4 5 5 5 5 6 6 6 7 8 7

Max. useful inlet pr

essur

e rise

p

in bar

in r

elation to the pump curve

inl,max .

bar

Fig. 15:

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5

5.2.3

Determining the pressure zones

Under normal operating conditions, a unit using continuous speed control ensures an almost constant discharge pressure p_discharge= 5.4 bar (see also section 5.2.2).

The following equation applies to the number of floors requiring protection (Nflpr):

[26]

5.4 bar - 5.0 bar N_flpr = ––––––––––––––

0.3 bar Nflpr = 1.3 앒 2

From this equation can be deduced that the lowest two floors, namely the basement and the ground floor, would require protection. However, the basement, ground floor as well as 1st_{and 2}nd floors are not connected to the PBU. Floors 3 to 10 do not, in principle, require any protection.

In the event of a fault: Speed control failure In this case, the following applies due to change-over to cascade operation:

[27]

pdischarge= p0 = 3.5 bar + 5.6 bar = 9.1 bar

Result of [27] inserted into equation no. [26]:

9.1 bar - 5.0 bar N_flpr = ––––––––––––––

0.3 bar

Nflpr = 13.6

This means that while in principle no floors

all floors connected to the PBU must be protected (see also section 5.2.2).

N_flpr = Number of floors which have to be protected against inadmissible pressures by means of pressure reducers

p_max = Maximum pressure ⌬pfl = Pressure loss per floor

p₀ = Maximum pump pressure at zero flow rate (Q = 0)

pinl,max = Maximum pressure upstream of the

PBU

H₀ = Maximum discharge head at zero flow rate (Q = 0)

Determining the max. floor pressure (pmax,fl) As in section 5.1.3, we take a static approach meaning we do not assume any flow losses Σ(R·l+Z).

Normal conditions: pdischarge = pci

In the event of a fault: pdischarge = p0

[28]

Example:

Floor 10 requires: ⌬p_{geo,10th floor}= 3.3 bar Normal conditions:

p_{max,10th floor} = 5.4 bar - 3.3 bar pmax,10th floor = 2.1 bar

In the event of a fault:

p_max,_{10th floor} = 9.1 bar - 3.3 bar pmax,10th floor = 5.8 bar

H₀

pdischarge= p0 = pinl,max+ –––––– [bar] 10

pmax,fl= pdischarge- ⌬Hgeo (floor x) [bar] p_discharge- p_max Nflpr = –––––––––––– ⌬pfl pdischarge- pmax Nflpr = –––––––––––– ⌬pfl

(27)

5

The other floor pressures can be calculated using the respective ⌬pgeovalues.

Legend for [28]:

pmax,fl = Maximum pressure per floor

pdischarge= Required pressure downstream of the

PBU

⌬Hgeo(floor X)= Static pressure loss for floor X.

Calculating the minimum flow pressure per floor

The same calculation as the one described in section 5.1.3 (Calculating the minimum flow pressure per floor) can be used.

The following applies to the 5th_floor: pmin,fl= 3.0 bar

5.2.4

PBU with one variable speed pump (Hyamat V) – Possible effects

In the event of a fault (breakdown of the variable speed control), the pressure rises on those floors not provided with additional safety equipment!

Conclusion:

In the event of a fault (variable speed control breakdown), the max. static pressure from floors 4 to 10 considerably exceeds the maximum set pressure of 5 bar.

Possible effects:

• Considerably increased flow velocity

• Float valves of cisterns cease to close

• At a pressure of 6 bar, the safety valves on the water heaters open. As a result of possible fluctuations, in-creased switching frequency of the pumps and even pressure surges are to be expected.

Possible remedial measures: • Installation of a central

pressure reducer downstream of the PBU (the value set for this downstream pressure must be > pci)

• Installation of a by-pass valve + temperature monitor in the by-pass pipe from the consumer to the inlet side Bottom pressure zone,

directly supplied via supply pressure Top pressure zone, supply via PBU

Basement Ground floor 10th 9th 8th 7th 6th 5th 4th 3rd 2nd 1st Hyamat V ± 0 m + 3.0 m + 6.0 m + 9.0 m + 12.0 m + 15.0 m + 18.0 m + 21.0 m + 24.0 m + 27.0 m + 30.0 m + 33.0 m = 2.1 bar

Normal operation Fault

= 2.4 bar = 2.7 bar = 3.0 bar = 3.3 bar = 3.6 bar = 3.9 bar = 4.2 bar = 1.0 bar = 1.4 bar = 1.8 bar = 2.2 bar = 2.6 bar = 3.0 bar = 3.4 bar = 3.8 bar = 2.2 bar = 9.1 bar in the event of a fault

= 1.0 bar = 1.4 bar = 1.8 bar = 3.5 bar = 5.4 bar = 2.6 bar = 2.9 bar = 3.2 bar 7.9 bar 7.6 bar 7.3 bar 7.0 bar 6.7 bar 6.4 bar 6.1 bar 5.8 bar W F p max,V pdischarge p max p max p max p max p max p max p max p max p max p max p max p min p min p min p min p min p min p min p min p min p min p min p min,V p 0,max

possible remedial measures: Section 5.2.2

Fig. 16

Schematic drawing of a PBU with one variable speed pump incl. pressure values and pressure zones

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5

5.2.5 Summary

The disadvantages of cascade operation are avoided. Generally, pressure reducers and large membrane-type accumulators are not necessary. Making full use of the inlet pressure saves electrical drive energy.

5.3

PBU with speed control on all pumps (Hyamat VP)

5.3.1 Features

• All pumps are variable speed

• Number of operating pumps depends on flow rate • No pressure rise in the event of a fault/variable

speed pump breakdown

• Broad regulating range, optimum conditions when all pumps are running

• Constant discharge pressure

• Compensation for very high inlet pressure fluctuations possible

• With regard to fluctuations during operation, the adverse hydraulic effects on the public water network are very low

5.3.2

Calculation example (also see section 5.2.2)

All calculations are performed as per section 5.1.2 and 5.2.2 in accordance with example (4)

pdischarge = pci = 5.4 bar

Even in the event of a fault, inadmissible pressure rises cannot occur with this type of PBU concept. Therefore, floors 3 to 10 can be directly connected to the PBU (Fig. 11) without any protective meas-ures. A constant discharge pressure pdischargeis guaranteed at all times.

5.3.3

Determining the pressure zones see also section 5.2.3

Nflpr = 1.3 앒 2

From this equation can be deduced that the lowest two floors, namely the basement and the ground floor, would require protection. As, however, the basement, ground floor as well as 1st_{and 2}nd floors are not connected to the PBU anyway this can be disregarded.

A special feature of this PBU concept is that even in the event of a fault (e.g. breakdown of one variable speed pump) a pressure rise is not to be expected. All other variable speed pumps continue operating. If required, the stand-by pump (also equipped with variable speed control) can be started up.

Hence, floors 3 to 10 are supplied with water without needing additional protective equipment.

Determining the maximum floor pressure pmax,fl

As in section 5.1.3, we take a static approach meaning we do not assume any flow losses Σ (R x l + Z).

Hyamat VP

continuously variable

Speed control on all pumps

p const. pci Q p 0 p _ci Q excessive on/off constant discharge pressure p _discharge H n pumps n -1 pumps Fig. 17:

Performance chart of a PBU with speed control

(29)

5

The following is therefore applicable:

[29]

[30]

Example:

The following is applicable for the 5th_floor: N = 6; ⌬p_geo,fl= 0.3 bar; p_discharge = 5.4 bar ⌬pgeo (floor 5)= N · ⌬pgeo,fl = 6 · 0.3 bar ⌬pgeo (floor 5) = 1.8 bar

therefore,

p_{max (floor 5)} = 5.4 bar - 1.8 bar p_{max (floor 5)} = 3.6 bar

pdischarge = Required pressure downstream of

the PBU

p_max,fl = Maximum pressure per floor

p_ci = Cut-in pressure / setpoint ⌬pgeo (floor X) = Static pressure loss for floor X

Determining the minimum floor pressure pmin,fl The following is also applicable for floor 5: p_{min (floor 5)} = 3.0 bar

5.3.4

PBU with speed control on all pumps (Hyamat VP) – Possible effects

All pumps are variable speed. In the event of a fault (breakdown of one variable speed pump), the Hyamat VP unit continues operat-ing with the available variable speed pumps.

The supply pressure is not subjected to any fluctuations.

Conclusion:

Additional measures are not re-quired.

In buildings with more than 10 floors, it is normal to define pressure zones.

5.3.5 Summary

Even if one frequency inverter unit breaks down, the discharge pressure remains constant (in the Hyamat V concept, by contrast, the PBU would automatically change over to cascade operation). Any hydraulic equipment limiting the pressure is not required.

Fig. 18

Schematic drawing of a PBU, all pumps are variable speed con-trolled, incl. pressure values and pressure zones

Bottom pressure zone, directly supplied via supply pressure Top pressure zone, supply via PBU

Basement Ground floor 10th 9th 8th 7th 6th 5th 4th 3rd 2nd 1st Hyamat VP ± 0 m + 3.0 m + 6.0 m + 9.0 m + 12.0 m + 15.0 m + 18.0 m + 21.0 m + 24.0 m + 27.0 m + 30.0 m + 33.0 m = 2.1 bar = 2.4 bar = 2.7 bar = 3.0 bar = 3.3 bar = 3.6 bar = 3.9 bar = 4.2 bar = 1.0 bar = 1.4 bar = 1.8 bar = 2.2 bar = 2.6 bar = 3.0 bar = 3.4 bar = 3.8 bar = 2.2 bar = 1.0 bar = 1.4 bar = 1.8 bar = 3.5 bar = 5.4 bar = 2.6 bar = 2.9 bar = 3.2 bar W F p max,V p discharge p max p max p max p max p max p max p max p max p max p max p max p min p min p min p min p min p min p min p min p min p min p min p min,V p_discharge= p_ci= constant [bar]

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6

Overview – Connection types for drinking water installations Overview – Connection types for drinking water installations

6

No adverse effects on supply network Demand peaks are covered

Constant inlet pressure

Risk of contamination

No risk of contamination Additional pressure loss Dampened impact on supply network

Constant inlet pressure Wasted energy

(max. +0,3/-0,2 bar)

Tank is not required Normally

not required

Observe pump curve profile

Observe pump curve profile Exploitation of design inlet pressure Inlet pressure fluctuation must be limited

Inlet pressure may fluctuate slightly

Full exploitation of inlet pressure

Greater inlet pressure fluctuation permitted

Full exploitation of inlet pressure

Inlet side Indirect connection Direct connection

Unpressurized tank for volume balancing

Flow is distributed across pumps according to demand Discharge pressure fluctuation Constant discharge pressure Wasted energy Optimum Good Possible Unfavourable Constant discharge pressure Minimum energy demand Constant discharge pressure Minimum energy demand Highly dynamic regulating potential No risk of contamination

Reduction of switching frequencies Additional pressure loss

Not required Pressure peaks are reduced

7

Overview – Connection types for fire-fighting units, wet risers

7

Overview – Connection types for fire-fighting units, wet risers

Seitenr

and

Direct-flow membrane-type accumulator with dual connection

Pressure reducer

Time-controlled solenoid valve Membrane-type accumulator Cascade-controlled

pump Risk of contamination

due to water stagnation. Tapping drinking water is not possible

Constant discharge pressure Pressure zones decentralized No DIN recommendation for pressure reducers

Switching frequency is limited (e. g. toilet flushing)

Adverse effects when tank is being filled and in the case of direct connection

Start-up via remote-electric controlled contact possible No excessive on/off during fire-fighting duty Consumer side

Fire hydrant

Fire hydrant with electric contact

Toilet used regularly ensures exchange of water WC WC WC WC Signal line Optimum Good Possible Unfavourable Legend

Unpressurized inlet tank Supply network To reduce the risk of back contamination it is important to ensure that time-controlled flushing of the fire-fighting system (1.5 x the pipe contents per week) takes place in directly connected pressure boosting units.

Pressure boosting system pressure-dependent control

pressure-dependent cascade control

Hya-Solo D*) Hya-Eco + Hyamat K*) *) p p pco pco pci pci Q Q FfW Fire-fighting water DW Drinking water Q Q_netw FfW must be lower than Exploitation of design inlet pressure Hydraulic separation

Storage of water

No adverse effects on supply netword

Constant inlet pressure

No DIN recommendation for pressure reducers Dampened effects on supply network

Inlet side Indirect connection Direct connection

Unpressurized tank for volume balancing

*Limited volume balancing as a standard, full volume balancing on option

Exploitation of design inlet pressure

Inlet pressure fluctuation has an influence on the system’s characteristics 7

(32)

Overview – Connection types for wet- / dry-type units

8

Overview – Connection types for combined installations

Cascade-controlled pump

Wall-mounted fire hydrant Variable speed pump

Drinking water valve To reduce the risk of contamination in the connection pipe it is important to ensure that time-controlled flushing of the fire-fighting pipe branch (1.5 times the pipe contents per week) takes place in drinking water operation (direct connection). Fire-fighting operation is activated via the contacts on the wall-mounted fire hydrants

**) *)

Contact Signal line

Pressure boosting unit

Cascade control

Cascade control for all pumps Arrangement example

One variable speed pump and pressure-dependent control of fire-fighting pump

One variable speed pump Hyamat K Hyamat K Hyamat V Hya-Solo D**) Hya-Solo D**) Hyamat V PBU p p p p Selection of economically determined pump sizes

Selection of economically determined pump sizes

pA p_E FL Ftw TW DW TW DW FL Ftw Set value Set value DFtwW Q Q Q Q *) *) Optimum Good Possible Unfavourable Legend W / D Optimum Good Possible Unfavourable Legend

Wet/dry valve station Pressure boosting unit

Cascade control Hyamat K Hya-Solo D Hyamat K PBU Arrangement example p p p p Δ Δ Fire-fighting pumps Filling pump p_A p_A pE pE Q Q W / D Cascade-controlled pump Wall-mounted fire hydrant *) *) *)

To reduce the risk of back contamination it is important to ensure that time-controlled flushing of the fire-fighting unit

(1.5 x the pipe contents per week) takes place in directly connected pressure boosting units. *)

8

Overview – Connection types for combined installations: Drinking water and fire-fighting water Service water and fire-fighting water

Seitenrand

9

N.B.: Depending on the specific unit conditions, the requirements for pressure boosting units must be agreed with the manufacturer.

The connection types and the installation of accumulators must be realized in compliance with the water provider’s and manufacturer’s specifications for the specific unit.

9

Overview – Connection types for wet- / dry-type units

NB: If special solutions are involved, specific unit requirements must be agreed with the manufacturer! The connection types must be determined in compliance with the water provider’s and manufacturer’s requirements.