WORKSHEETS AND TABLES
Worksheet 6.A(M)— User Group—Example Temperature at Outlet a (°C)
A B C (L/Sec = A × B L/H = A × B × C × 60 Sec/Min) Min ___________41° ___________43° ___________60° ___________Other Fixture Qty. L/Sec Use/H L/Sec L/H L/Sec L/H L/Sec L/H L/Sec L/H Bathroom group
Usage Factors (UF) (Refer to Table 6.2):
User Group Totals (UF x Totals); Transfer to Worksheet 6.B
Note: L/sec calculation is for a semi-instantaneous water heating system. L/h calculation is for a storage type water heating system.
aTemperatures are at faucet outlet NOT system temperature.
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(Worksheet 6.A[M] Example continued)
bBased on ANSI standards of 0.16 L/sec for showerheads, 0.16 L/sec for sinks, 0.13 L/sec for lavatories, and 0.03 L/sec for public lavatories.
cBased on the shower as the dominant fixture.
dBased on the valve size used. Designer must base design on the type of valve that is specified or present in an existing facility.
eSame as “d” except two baths per hour.
fBased on 0.28 L/sec and DN15 hot water supply running full open at 1.83 m/sec maximum velocity.
gConsidered same as shower.
h0.57 L/sec based on DN20 hot water supply running full open at 1.83 m/
sec maximum velocity.
iBased on Table 6.1, “General Purpose Hot Water Requirements for Various Kitchen Uses” (L/h).
jBased on the equipment used. Designer must determine which model is used.
kWhere a dash (—) appears, please refer to Table 6.1 for the recommended hourly use figure.
lAn asterisk (*) indicates the recommended outlet temperature.
Table 6.1— General Purpose Hot Water Requirements for Various Kitchen Uses
This table, which supplies information on the hot water require-ments for various kitchen uses, should be used for the dietary and food service user group.
Table 6.1 General Purpose Hot Water Requirements for Various Kitchen Uses
Equipment GPH L/H
Vegetable sink 45 170.33
Single compartment sink 30 113.55
Double compartment sink 60 227.10
Triple compartment sink 90 340.65
Prescrapper (open type) 180 681.30
Prerinse (hand operated) 45 170.33
Prerinse (closed type) 240 908.40
Recirculating prerinse 40 151.40
Bar sink 30 113.55
Lavatories 5 18.93
Source: Values are extracted from Dunn et al. [1959] 1989. Chapter 4. ASPE Data Book. Table 9.
Note: Requirements are for water at 140ºF (60ºC).
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Table 6.2— Usage Factors for User Groups
This table provides the recommended usage factors for use with Worksheet 6.A. The following discussion gives the background of how these numbers were determined. (They represent a consen-sus of opinion of experienced designers; however, designers should use their best judgment when working with these figures):
General
The “gpm (L/sec)” figure is based on the possibility that every hot water using fixture will be operated in any 1 min (sec). The “gph (L/h)” figure is based on the possibility that every hot water us-ing fixture will be operated durus-ing a 1-h period. These figures are based on a peak usage hour with a 3-h peak period.
Table 6.2 Usage Factors for User Groups User Groups
Dietary & Central
Patient Nurses’ Hydro- Food Surgical Sterile Obstetrics/ Misc.
Area Station therapy Service Suite Supply Nursery Areas GPM (L/Sec) 0.10 0.05 0.25 0.40 0.50 0.20 0.10 0.05 GPH (L/H) 0.40 0.50 0.90 0.90 0.50 0.90 0.40 0.10 Note: Based on a peak usage hour with a 3-h peak period.
Patient area
This user group is split into two areas, surgical and medical pa-tient areas. Many papa-tients in these areas are not ambulatory and require assistance from the staff to use the toilet or the bathing facilities. Many surgical patients are not allowed to use the shower or bathing facilities until approximately the second day after sur-gery. Medical patients are often not allowed to use the facilities until after their conditions improve. Because of this, many are sponge bathed. The lavatory is a fixture that is heavily used by the staff.
The 0.10 (10%) usage factor for the gpm (L/sec) is based on only the shower being in use (i.e., the lavatory is not in use dur-ing the same minute). Also, it is assumed that not all the patients are using the fixtures during the same minute.
The 0.40 (40%) usage factor for the gph (L/h) is based on either the shower or the lavatory being used in an hour during
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peak usage time. Because the lavatory uses less water than the shower, the factor is less than 0.50 (50%).
Nurses’ station
This user group is in use 24 h a day but typically is used most heavily during shift changes. This is because of the preparation necessary before patients can be aided.
The 0.05 (5%) usage factor for the gpm (L/sec) is based on the relationship between the staff and patients. During a peak 3-h period of 3-hot water use, t3-he patient area is used more 3-heavily than the nurses’ station. Since many patients need assistance using the bathing or shower facilities, staff members are in the patient areas aiding patients and not at the nurses’ station using the fixtures there.
The 0.5 (50%) usage factor for the gph (L/h) is based on these same issues, but because of the time staff members spend at the nurses’ station organizing or distributing medicines and doing other work, the hand washing fixtures there are heavily used.
Hydrotherapy
When in operation, this area is a large water user. The staff can be split between the physical and hydrotherapy areas.
The 0.25 (25%) usage factor for the gpm (L/sec) is based on the cyclical use of the therapy tubs and on the assumption that staff members also are doing physical therapy.
The 0.90 (90%) usage factor for the gph (L/h) is based on the assumption that during peak usage times almost all the fixtures in this area are used. That assumes that the staff schedules wa-ter therapies during one time and physical therapies during another.
Dietary and food service
This area is a large water user. Depending on the size of the facility, the usage of water for food preparation and for cleaning may overlap.
The 0.40 (40%) usage factor for the gpm (L/sec) is based on the assumption that cleaning (the washing of dishes, etc.) does not occur in the same minute as food preparation. Also, it as-sumes that the sinks are filled and then work is done using an intermittent, not a steady, water supply.
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The 0.90 (90%) usage factor for the gph (L/h) is based on the assumption that most of the area fixtures are used during one of the hours of the facility’s peak usage time.
Surgical suite
Surgical procedures account for the majority of the time this area is in use. Though the scrub sinks are used intermittently during a procedure (e.g., staff leaving the room and returning will scrub again), the showers and scrub sinks are typically not used con-currently.
The 0.50 (50%) usage factor for both the gpm (L/sec) and gph (L/h) are based on the above scenario. During any 1 min or h of the facility’s peak usage period, either the scrub sinks or the showers are in use.
Central sterile supply
This area, which houses washing equipment, is in use during the facility’s peak usage time.
The 0.20 (20%) usage factor for the gpm (L/sec) is based on the assumption that some of the equipment is in a fill cycle dur-ing any 1 min. Due to the nature of equipment cycles, all the equipment does not use water during the same minute.
The 0.90 (90%) usage factor for the gph (L/h) is based on most of the equipment being used in the facility’s peak usage hour.
Obstetrics/Nursery
This user group is in use 24 h a day. The birth process and resting afterward typically account for the majority of a patient’s time in this area. Showers are sometimes taken dur-ing labor to relax the mother, and the hand washdur-ing lavatory is used extensively during labor by the staff.
The 0.10 (10%) gpm (L/sec) usage factor is based on usage in the patient area. Though a patient in the obstetrics (OB)/nurs-ery area bathes after a birth, there is no set schedule for this because of the unpredictable nature of the birth process. Thus, at any 1 min, only 10% of the fixtures in this area are operated.
(This is part of the reasoning for the 5% factor used for the nurses’
station. Fixtures in the OB/nursery user group typically are used by staff members, implying that those workers are not concur-rently at the nurses’ station using fixtures there.)
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The 0.40 (40%) gph (L/h) usage factor also is based on the patient wing area. Also, many patients remain in the birthing rooms after delivery. (They’re not transferred to separate post-partum rooms.) Because of this, lavatories are used during labor by the staff and bathing or shower facilities are used by patients during the peak usage period. Both fixtures are not used exten-sively during the same hour.
Miscellaneous areas (e.g., lab, administration, maintenance, autopsy, the morgue)
The rest of the facility uses water but not during the facility’s peak usage time and not as much as those areas already discussed. This is because most of the staff are not in the miscel-laneous areas. These areas must be taken into account, however, because water using fixtures are available and used there.
The 0.05 (5%) usage factor for the gpm (L/sec) is based on the assumption that only a minor number of the fixtures are used during any 1 min of the facility’s peak usage time.
The 0.10 (10%) usage factor for the gph (L/h) is based on the assumption that most of the fixtures in these areas are used outside of the facility’s peak usage hour.
The designer must determine the usage pattern for each mis-cellaneous area.