221,0E
PRECIPITATION GAUGES AND RECORDERS
Rain and Snow Gauges
Mechanical Rain Recorders
Recording Precipitation Balance
for Rain and Snow
Rain and Snow Gauges
The Rain-Gauge 69d (fig.1) consists of a cylindrical upper part, serving as receiver, whose aperture forms the receiving area as well as a lower part with the collecting can. The rain which falls through the aperture is led into the inner collecting can via a funnel. To avoid an extreme evaporation of the collected rain water in the collecting can, the latter is set up free all round, so that a direct heat conduction from the radiated casing to the collecting can is prevented by the surrounding air.
The Rain- and Snow Gauge 69 differs from the prescribed type only in that way, that all parts as upper part, lower part, collecting can and snow cross, necessary for transformation of snow in the form of liquid water, are presented twice. The time required for the melting process is not lost therefore for continuous receiving of precipitation. In the case of snowfall the snow cross has to be put into the upper part to prevent whirling out of the snow by influence of the wind.
In order to measure the height of rainfall, one takes the upper part from the hook, removes the collecting can from the lower part and empties the same into the measuring cylinder. The height of precipita-tion in mm rainfall is read off directly on the scale of the measuring cylinder; the scale is graduated from 0 to 10 mm of rainfall in intervals of 0.1 mm.
In the case of type 69 the observer exchanges the whole instrument after snowfall against an empty one. Then the snowfilled rain gauge is closed by the cover and taken into a warmer room. After melting the snow, the height of the melted snow may be determined by means of the measuring cylinder.
Both types of instruments should expediently be mounted on plane terrain in such a way that the distance away from every surrounding object should be not less than twice the height of the object. This applies especially to the weatherside. The Rain Gauge is screwed by means of pertaining holder to a post in such a way that the receiving area lies horizontally and 1 m above the ground. In the case of unstable weather, there exists the possibility that a drift of atmospheric precipitation, as it may present itself at the casing's jacket by formation of a whirl, may lead to a deficit of the collected quantity of precipitation, as compared to the actually fallen quantity. Such errors in measurement can be avoided with the aid of wind shield 69w according to Woelfle, which consists of a shield of 840 mm diameter with 16 elastic blades. A joint support carries instrument and wind shield, with four stays orientating the latter towards the receiving area. The whole equipment is fastened to a tubic support of approximately 75 mm diameter which, itself, however, is not part of the delivery, in general.
Fig. 1 Rain Gauge
Specifications
69d Rain Gauge, Hellmann type with receiving area of 200 cm², consisting of:
1 upper part 1 lower part
1 collecting can ( = No. 69t) 1 support ( = No. 69v)
1 measuring cylinder ( = No. RM25 T171) Dimensions: 190 mm diameter x 440 mm height. Weight: 2.7 kg
69 Rain and Snow Gauge, Hellmann type with receiving area of 200 cm² consisting of:
2 upper parts 2 lower parts
2 collecting cans ( = No. 69t) 1 support ( = No. 69v)
1 measuring cylinder ( = No. RM25 T171) 2 snow crosses ( = No. 69u)
1 protective cover.
Dimensions: 190 mm diameter x 440 mm height, each. Weight: 4.7 kg
Supplementary and Spare Parts
Rm25 T171 (=No. 69m)
Measuring cylinder
for raingage with 200 cm² receiving area, for 10 mm rainfall,
divisioned in 0.1 mm of rainfall, according DIN 58667B, made from Polystyrol
69t Collecting can, capacity 1.4 litres corresponding to 70 mm of rainfall.
69u Snow cross.
69v Holder for suspension of rain gauge.
Mechanical Rain Recorders
Whilst simple rain gauges and rain recorders, solely, indicate the total quantity of precipitation during the period of observation, the structure of rainfall is to be seen additionally from the diagram of a rain recorder; i. e., the timely division, intensity, etc. An example as to the relation of these values indicates table 1, which shows how the average number of yearly rainfall decreases with increasing intensity and duration.
Table 1. Intensity, duration, and frequency of rainfall in Kempten, Allgäu,
during an observation period of 23 years, as acc. to Haeuser, J.: "Abhandlung der Bayrischen Landesstelle für Gewässerkunde", München, 1919 (Treatise of the State Institute of Hydrology for Bavaria, Munich). The mean yearly quantity of precipitation in Kempten amounts to appr. 1470 mm.
Intensity of Rainfall
mm of Rainfall per min ≥
0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 1,2 1,4 1,6 1,8 2,0 2,6 3,0 3,4
Litres per Hektar and sec ≤
17 35 52 68 85 1,2 118 135 152 168 202 235 268 302 335 435 502 568
Duration of Rainfall
Average Number of Rainfalls during a Year’s Time
1...5 min - 16,9 12,6 9,6 7,4 6,0 4,7 4,1 3,4 2,7 1,9 1,2 1,0 0,6 0,3 0,13 0,09 0,04 6...10 min - 12,0 7,8 4,9 3,9 3,0 2,4 1,7 1,3 0,7 0,5 0,3 0,2 0,1 0,1 - - - 11...20 min - 8,1 4,4 2,8 2,0 1,4 1,0 0,6 0,5 0,4 0,3 0,2 0,1- 0,04 - - - - 21...30 min 11,1 3,3 1,8 1,7 0,9 0,4 0,4 0,4 0,3 0,2 0,04 - - - - 31...45 min 9,0 2,3 1,3 0,7 0,5 0,2 0,2 0,1 - - - - 46...60 min 5,2 1,1 0,7 0,4 0,2 - - - - 1...2 hrs 2,9 0,9 0,4 0,13 0,1 - - - - 2...3 hrs 0,9 0,3 0,04 - - - - Over 3 hrs 0,5 0,13 - - - -
Three types of mechanical rain recorders are available for the different fields of application, which, with respect to receiving area and speed of recording, may be varied, yet. When making one's choice, one is always to consider the goal of measurement. Thus, for instance, one will be able to dispense, in climatological investigation, with the optimum of resolution of heavy rains which, already, present themselves only seldom, and which are of short duration. For the sewerage engineer, on the other hand, these extremes are of special importance; e. g., for dimensioning the cross section of conduits, etc.
Fig. 3 Measuring Principle
of Mechanical Rain Recorder 95. A aperture ring B float vessel C float D casing H siphon K collecting vessel Z pen arm
The Mechanical Rain Recorders 95, 95y, and 95c, differ from one another in the essential by height and kind of recording. The measuring system is constructed in a similar way, in the case of all these types. As is shown in fig. 3, the round casing D carries above a sharp-edged aperture ring A, which, normally, limits the receiving area to 200 cm². The fallen-in rain flows into the cylindrical float vessel B, lifting the float C. The motion of this latter is transmitted to the pen by means of a float rod carrying the pen arm Z.
There results, thus, a trace on the diagram paper moving evenly under the pen, the more or less steep ascent of which corresponds to the momentary intensity of rainfall (fig. 4). At a certain fallen-in quantity of rafallen-in, the pen has reached the maximum value of the range. Via a correspondfallen-ingly adjusted siphon H, the float vessel B is, now, being emptied within the shortest possible time, the pen arm returns to its zero-position, and the process may start, anew.
The diagram may be evaluated at will; i. e., corresponding to the respective factors, which are of interest. An additional control of the recording is possible, also, as the water, which has flown out through siphon H, is in collecting vessel K and, therefore, the total quantity of precipitation may be determined by means of a measuringcylinder
Each siphoning of the float vessel is marked on the chart by a vertical interruption. If one takes as a basis that a distance of these verticals of 1 mm still allows for evaluation, one will understand that the as yet resolvable maximum intensity of rainfall is depending upon the speed of recording. One is to consider this when choosing the clockwork.
Normally, all mechanical rain recorders are supplied with a receiving area of 200 cm². If one reduces the receiving area by means of an exchangeable aperture ring No. 95r to 100 cm², the maximum intensity, which may be covered, is doubled, naturally. The indications of the diagram are, then, to be multiplied by the factor 2. This supplementary item, which can be supplied additionally, on request, allows for adjustment to special local or seasonal requirements, therefore. Table 2, on page 7, is giving a survey of the technical data available by the three models and shows the different combinations by the possibilities of variation.
If one is to avoid that, in the case of temperatures below 0 °C, the apparatus is no longer ready for operation, Electric Heating device 95d can be fitted, even subsequently, if the case may be. In the case of this device, a thermostat controls the switch of the two incorporated electric bulbs so that temperature within the casing is kept at an approximately constant value above the freezing point. Switching temperature is adjustable on a scale. If the heating device is used, it is recommendable, however, to provide the rain recorder with an additional wooden cabinet, as, otherwise, the loss of warmth will be rather large.
Fig. 4 Part of an original
Recording of Mechanical Rain Recorder 95.
One half of natural size (chart No. 2, for daily rotation)
Rain Recorder 95,
Hellmann Type (Standard Model)An illustration of this model, with drum recording, shows the cover picture, and the pattern of a chart, fig. 4. Effective recording height is 78 mm for 10 mm of rainfall. Recording is effected, therefore, appr. eight times enlarged.
In the case of the usual daily rotation, the vertical lines of the recording lie, even at the high and rare intensity of rainfall for Central Europe of 2.7 mm/min, at a distance of 1 mm from each other so that these heavy rains, too, are still resolved well. A clockwork for a rotation period of 1 week can be supplied. The technical data please take from table 2, page 8.
Large Rain Recorder 95y
This instrument differs from model 95 in the essential by twice as large values of drum diameter, float vessel section, and effective recording height. By these measures, resolution of heavy rains is better by the factor 8, whilst recording is effected about four times enlarged. 40 mm of rainfall correspond to 156 mm of recording. In the case of daily rotation, intensities up to 20 mm/min are resolved. Further technical data, also for rotation periods of 1 week and 1 month, are shown in table 2, as well as in the specifications.
Rain Recorder 95c
with Continuous Chart Recording
Utilization of this rain recorder is to be recommended when it is necessary to, quantitatively, cover precipitation over a longer period of time or to record, most accurately, the timely course.
The well-proven measuring principle has been adapted, unchanged, from Rain Recorder 95, the rotating drum,
.however, replaced by a continuous chart recording me-chanism with hand-wound spring chart drive or battery operated spring chart drive or synchronous motor-operated spring chart drive (fig. 5). Also in the case of longer periods of recording is a large paperfeed applicable, therefore, which guarantees high evaluation even in the case of heavy rains. The continuous chart has a length of about 18 metres. By exchanging gear wheels, one may, according to choice, adjust paperfeed speeds of 5, 10 or 20 mm/h. All technical data are shown in table 2 or in the specifications.
Rain Recorder 95 Large Rain Recorder 95y
Rain Recorder 95c with Continuous Chart Recording
Range per Height of Diagram (mm of rainfall) 0 to 10 (20)1) 0 to 40 (80)1) 0 to 10 (20)1) Receiving Area (cm)2 200 (100)1) 200 (100)1) 200 (100)1) Drum Diameter (mm) 133 264 - Height of Recording (mm) 78 156 78 Recording Period
(Paper running time) 26 h 7 1/3 d 31 d 26h 7 1/3 d 31 d 36 d 5
) 72 d 5) 144 d 5) Paperfeed appr.
(mm/h) 16 2,3 0,5 32 4,5 1 20 101) 51)
Running Period of the
chart drive 9 d 9 d 32 d 9 d 9 d 32 d 32 d 32 d or 96 d3) 32 d or 96 d3) Maximum Intensity2) (mm rain/h) 27 (5,4)1) 0,3 (0,7)1) 0,1 (0,2)1) 20 2,7 (5.4)1) 0,6 (1,2)1) 3,3 (6,7)1) 1,7 (3,3)1) 0,8 (1,7)1) Chart No. 2 3 39 2 k 2 i 4 e 95/20 95/10 95/5
Number of Charts per
Set 100 54 14 100 54 14 10 rolls 10 rolls 10 rolls
1) Parenthetical values refer to a receiving area of 100 cm2.
2) Intensity, at which the vertical lines of the diagramm draw nearer to a distance of 1 mm. 3) Only to special order.
4) In the case of running period of 96 days only these paperfedds are to be delivered.
It is to be noticed, that the operating-period is determined either by the running period of the chart drive or by the paper running time. Full utilization of the paper running time is only possible with battery motor-operated or synchronous motor-operated spring chart drive
Fig. 5 Principle of desing Rain Recorder 95c with Continous
Chart Recording.
1 aperture ring, 2 float, 3 siphon, 4 collecting vessel, 5 protective funnel, 6 drain cock, 7 continous chart, 8 casing with door
The glass capillary pen used for recording stands out for its large reserve of ink and for its economical consumption. Attendance of the instrument is required only once per month and, therefore, is especially suited for installation at remote or difficult accessible measuring points.
Specifications
No.
95 Mechanical Rain Recorder, Hellmann Type (Standard Model) , complete, technical data as per table 2.
Recording period: according to choice 26 hours
7 1/3 days 31 days
Dimensions: body: 240 mm, total diameter 370mm x 1000 mm height. Weight: 11 kg (without packing)
Accessories (no extra charge):
1 set of charts, 1 spare-cartridge-pen, 1 measuring cylinder Rm25 T171, 1 collecting vessel Rm25 UG29, 1 glass siphon Rm25 UG12 spare, 1 protective cover.
95y Large Rain Recorder, complete, technical data as per table 2. Recording period: according to choice
26 hours 7 1/3 days 31 days
Dimensions: 380 mm diameter x 1190 mm height. Weight: 28.0 kg.
Accessories (no extra charge): as for No. 95, but with collecting vessel 95k4 and spare glass siphon RM25 UG10
95c Rain Recorder with Continuous Chart Recording, with hand-wound spring chart drive complete, technical data as per table 2.
Running period: 32 days Paperfeed: according to choice 20 mm/h
10 mm/h 5 mm/h
Running period: 96 days Paperfeed: according to choice 10 mm/h
5 mm/h
Rain Recorder with Continuous Chart Recording, however with battery motor-operated spring chart drive.
Paperfeed: 5, 10 or 20 mm/h according to choice
Rain Recorder with Continuous Chart Recording, as forementioned, however with synchronous motor-operated spring chart drive.
Paperfeed as forementioned
Dimensions: 380 mm diameter x 1190 mm height Weight: 30 kg.
Accessories (no extra charge):
10 rolls of diagram paper, 1 bottle of special ink 1095v, 1 glass-capillary pen 95q, spare, 1 collecting vessel 95k5, 1 measuring cylinder Rm25 T171, 1 glass siphon Rm25 UG12, 1 protective cover.
Supplementary and Spare Parts for all Rain Recorders
95r
Exchangeable aperture ring for reduction of receiving area from 200 to 100 cm² Weight: 0.6 kg.
95d Electric heating device with thermostat.
95dT Thermostat for 95d.
95s Snow cross.
Rm25 T171 (=No. 69m) Measuring cylinder, for raingage with 200 cm² receiving area, for 10 mm rainfall,
divisioned in 0.1 mm of rainfall,
according DIN 58667B, made from Polystyrol
Supplementary and Spare Parts, especially for Rain Recorder 95
95w Wind shield.
95p Pair of change gears for alteration of rotation from 1 month in 1 week.
78wfd Spare-cartridge-pen.
78q Spare metal-pen.
1095v 1 bottle of special recording ink (20 ml)
Rm25 UG12 (=No. 95o) Glass siphon, spare. (275 mm)
Rm25 UG29 (=No. 95k3) Collecting vessel, spare, capacity 3 litres corresponding to 150 mm of rainfall. Rm25 UG06 (=No. 95ea) Pen arm with guidance.
Rm25 UG05 (=No. 95ec) Float with guide rod, spare.
Rm25 UG03 (=No. 95ef) Float vessel with float and pen arm.
306d Spare drum with clock-drive for 1-day’s rotation.
306w Spare drum with clock-drive for 1-week’s rotation.
Supplementary and Spare Parts, especially for Large Rain Recorder 95y
Rm4 UG06 (=No. 95eb) Pen arm with guidance. Rm4 UG05 (=No. 95ed) Float with guide rod, spare. Rm4 UG03 (=No. 95eg) Float vessel with float pen arm.
Rm25 UG10 (= No. 95i) Glass siphon, spare (in the case of collecting vessel 95k4). (350mm) Rm25 UG12 (=No. 95o) Glass siphon, spare (in the case of collecting vessel 95k11). (275 mm)
Rm4 UG29 (=No. 95k4) Collecting vessel, spare, capacity 4.5 litres corresponding to 225 mm of rainfall. 95k11 Collecting vessel, spare, capacity 11 litres corresponding to 550 mm of rainfall.
95py Pair of change gears for alteration of rotation from 1 month in 1 week.
95L Spare pen.
78wfd Spare-cartridge-pen.
78q Spare metal-pen.
Supplementary and Spare Parts, especially for Rain Recorder 95c with Continuous Chart Recording
95cw Wind shield for No. 95c and 95y.
95q Glass capillary pen, spare.
Rm25 UG12 (=No. 95o) Glass siphon, spare. (350mm)
95k5 Collecting vessel, spare, capacity 5 litres corresponding to 250 mm of rainfall.
95k16 Collecting vessel, capacity 16 litres corresponding to 800 mm of rainfall, with measuring rod.
95g5 Pair of change gears for paperfeed of 5 mm/h.
95g10 Pair of change gears for paperfeed of 10 mm/h.
95g20 Pair of change gears for paperfeed of 20 mm/h.
Rm25 UG06 (=No. 95ea) Pen arm with guidance.
Rm25 UG05 (=No. 95ec) Float with guide rod, spare.
Recording Precipitation Balance 95ab for Rain and Snow
Recording Precipitation Balance 95ab is suited for coverage by measurement of whatever kind of atmospheric precipitation. Its recordings, largely, supply information, not only as to the total of precipitation but also about the structure, duration, intensity, and frequency of same. Losses, as may present themselves by evaporation, can be taken into account, when evaluating the diagram, as the curve is rectrograde, then.
Utilization of Precipitation Balance 95ab is especially recommendable in places, in which an essential quantity of the precipitation is presenting itself as snow. The instrument is a further development of the Hellmann type snow balance but shows a number of essential advantages in comparison with this predecessor. May we point out here, only, its larger capacity, and its high degree of operating reliability. Thus, the instrument may be installed also in places, which are seldom visited. Heating for operation is not required.
The outer shape of Precipitation Balance 95ab corresponds to that of Rain Recorder 95. Here, too, the round sheet iron casing carries a sharpedged ring above, which borders the receiving area. Normally, the receiving area is of 200 cm2. It may, easily, be altered, however, to larger or smaller values by exchanging the attachment with the aperture ring.
The precipitation fallen enters, directly, into a cylindrical receiving vessel which is borne by one leg of an inclined balance. Measuring principle in this case is weighing of the precipitation, therefore. The balance beam is provided with a turnable axle, which runs in easy movable ball bearings of rustproof steel. All bearings are embedded in a dustproof kind of way and oiled in anti-freezing fashion so that the high degree of response of the balance is guaranteed in the case of low temperatures, as well as after a long period of operation.
The system for transmitting motion of the balance to the pen arm is so designed that, in the case of increasing precipitation, the pen arm, starting from the lower border of the chart, moves towards the upper border of same, where it reverses, automatically, and, recording in reversed sense, runs back to the lower border of the chart. In this way, recording height of 160 mm is traversed twice, and capacity of the instrument is doubled. Recording is effected by ink, in curvature co-ordinates.
As the drum with the diagram paper is rotating symmetrically, the trace of a curve results which, starting from the lower border of the chart, more or less steeply climbing, corresponding to the intensity of precipitation, continues to the upper border of same. In case of further increasing precipitation, it turns downwards, until, after reaching the lower border of the diagram again and traversing the total of recording height twice, i. e., 2 x 160 mm = 320 mm, the maximum of capacity of the instrument is reached.
The cylindrical receiving vessel may easily be removed for the purpose of emptying or exchanging. If one intends to cover all precipitation without loss, as far as possible, it is recommendable to use the two of the supplied receiving vessels alternately. This makes it possible, also for control of the recording, to determine the quantity of precipitation fallen by means of a measuring cylinder, after precipitation in solid form has been melted.
At a diameter of 133 mm the drum has a height of 186 mm. By using a special driving mechanism, reliable running of the drum is guaranteed, also at low temperatures. According to the used pair of change gears, rotation is effected in 1 week, 2 weeks or in 1 month (table 3). The period of running is, in every case, approximately 35 days. The requested time for rotation must be indicated, when ordering. By exchanging the pair of change gears, however, the time of rotation may be altered also subsequently.
Recording Precipitation Balance can be supplied by request with Continuous Chart Recording Mechanism, see specifications No. 95ac.
Normally, a receiving area of 200 cm² is provided for the precipitation balance. On request, receiving areas of 100 cm² or 400 cm² may be supplied, too. Table 4 informs about measuring ranges and recording scales available with the various receiving areas.
Against on extra charge, the instrument can be equipped also with a wind shield 95aw, the function of which corresponds to that of the wind shield 69w. It may be fastened also subsequently on the cylindrical casing jacket beneath the aperture ring.
Specifications
No.
95ab Recording Precipitation Balance, with drum recording, complete. Receiving area: 200 cm².
Measuring range: 0 to 160 mm of rainfall. Gauge scale 2:1.
Recording drum: 133 mm diameter x 186 height.
Effective height of recording: 320 mm (traversing twice recording height of chart of 160 mm). Drum drive: Non freezable hand wound spring work.
Running period: appr. 35 days. Recording period; acc. to choice 7 1/3 days (paperfeed 2.2 mm/h) 14 2/3 days (paperfeed 1.1 mm/h) 32 days (paperfeed 0.55 mm/h).
Dimensions fo casing: 380 mm diameter x 1200 mm height. Weight: 36 kg.
Accessories (no extra charge): 1 second receiving vessel 95x, 1 set of charts, 1 bottle of special ink 1095v, 1 spare pen 78q, 1 pen cleaner, 1 protective cover
95ac Recording Precipitation Balance, as forementioned, however with Continuous Chart Recording, with hand-wound spring chart drive or with battery motor-operated or sychronous motor-operated spring chart drive.
Supplementary and Spare Parts
95x Receiving vessel, spare.
78q Spare metal pen.
95aw Wind shield.
1095v 1 Bottle of special ink.
Charts:
5b 1 Set = 54 charts for recording period of 1 week.
5c 1 Set = 30 charts for recording period of 2 weeks.
5d 1 Set = 14 charts for recording period of 1 month.
Exchangeable Aperture Ring for Changing Receiving Area:
95u1 Receiving area 100 cm2: range 320 mm of rainfall.
95u2 Receiving area 200 cm2: range 160 mm of rainfall.
95u4 Receiving area 400 cm2: range 80 mm of rainfall.
Pairs of Change Gears for Altering Rotation of Drum:
95p1 Rotation 1 week.
95p2 Rotation 2 weeks.
95p4 Rotation 1 month.
Table 3. Technical Data for Recording Precipitation Balance 95ab.
Recording period Pairs of change gears Paperfeed appr. mm/h Replacement of chart after Clock to be wound up after Chart No. 7 1/3 d 95p1 2.2 1 week 1 month 5b 14 2/3 d 95p2 1.1 2 weeks 1 month 5c 32 d 95p4 0.5 1 month 1 month 5d Table 4
Receiving Area and Measuring Ranges for Precipitation Balance 95ab with different Receiving Areas.
Receiving Area (cm²) Gauge Scale Recording Height/Rainfall Range mm of Rainfall 400 4:1 80 200 2:1 160 100 1:1 320 DR. ALFRED MÜLLER METEOROLOGISCHE INSTRUMENTE KG Tel.: +49 3375 9025-32 Fax: +49 3375 9025-36 Chausseestraße 39 / 42c D-15712 Königs Wusterhausen e-mail: [email protected] www.rfuess-mueller.de