Young Precipitation Gauge No Moving Parts Model 50202 - Manual (Page 3)

Page 2
50202-90(D)
INSTALLATION
The Model 50202 / 50203 is fully calibrated at the factory before
shipment, but does require care in the installation and initial priming of
the gauge. The following procedure should be followed.
1. The gauge is designed to installed on a vertical pipe mounting.
The mounting U-bolts are intended for use with ¾ inch to 1½ inch
Standard Iron Pipe Size (1.05 in to 1.90 in / 26.7 mm to 48.3 mm)
2. The base of the mounting pipe should be firmly anchored on a
level surface so that the sides of the gauge are vertical and the
top of the catchment is horizontal.
3. Slide both Mounting Bracket Assemblies (Part No. 50220) over
the mounting pipe.
4. Secure the U-bolt of the upper bracket near the top of the
mounting pipe. The mounting pipe should not extend above the
top of the gauge.
5. Mount the gauge itself on the upper bracket.
6. Slide the lower bracket up so that it engages the lower support of
the gauge.
7. Tighten the lower bracket.
8. Tighten the bolts that secure the brackets to the side of the gauge.
9. Verify the top of the catchment is horizontal. If not loosen the
mounting U-bolts and adjust accordingly.
10. Loosen the 3 thumb nuts on the side of the gauge to gain access
to the terminal strip for wiring the power, signal, and heater (Model
50202 only) wires.
11. Carefully slide the upper Catchment Assembly (Part No. 50230)
up to expose the terminal strip.
12. Connect wires according to enclosed wiring diagram.
13. Before operation the gauge must be primed to provide the
necessary reservoir in the bottom of the gauge.
14. Over a 1 minute period slowly pour approximately 500 ml of water
into the catchment.
15. When the measuring tube is full, the siphoning action will begin
and water will be discharged out the bottom of the gauge. Stop
pouring water into the catchment at this time.
16. The gauge is now ready for operation
17. Connect the power source and signal wires on the other end of
the cable to the data logger or display.
MAINTENANCE
The gauge should be inspected periodically. Accumulated dirt and
debris should be cleaned from the catchment area and screen (Part
No. 50238). The Measuring Tube Assembly (Part No. 50240) may be
removed for cleaning, but this would only be required on a much longer
interval.
CALIBRATION
1. VOLUME CALIBRATION CHECK
1.1 EQUIPMENT NEEDED
Water
500 ml graduated cylinder
25 ml syringe
1.2 PROCEDURE
1.2.1 PRIME GAUGE
a) Pour water slowly into catchment funnel until unit self
siphons.
1.2.2 MEASURE VOLUME
a) Pour 490 ml of water into catchment funnel.
b) Use syringe to add 5 ml of water very slowly. Measuring
tube should be nearly full.
c) Use syringe to add more water very slowly. Siphoning
should begin before 10 ml is added: tolerance is 495
- 505 ml, (±1%). Catchment funnel is 100 cm 2 and
measuring tube is 20 cm 2 (5:1 ratio). 1 mm of collected
precipitation equals 5 mm of masuring tube depth.
2 ELECTRONIC CALIBRATION
2.1 EQUIPMENT NEEDED
Water
500 ml graduated cylinder
Fixed DC power source (12 to 24 VDC)
Voltmeter
25ml syringe
2.2 PROCEDURE
2.2.1 MAKE ELECTRICAL CONNECTIONS
a) Refer to wiring diagram for proper connections.
b) Connect 12 to 24 VDC to power input.
c) Connect a voltmeter to circuit output.
2.2.2 PRIME GAUGE
a) Pour water slowly into the catchment funnel until the unit
self siphons.
2.2.3 CALIBRATE VOLTAGE OUTPUT FOR ZERO
a) Turn ZERO trimpot (R4) on circuit board until a positive
change is observed in the voltage output.
b) Then turn trimpot until voltage output just reaches 00.0
volts. Do not turn it any further.
2.2.4 CALIBRATE VOLTAGE OUTPUT FOR FULL SCALE
a) Pour 450 ml into catchment funnel.
b) Adjust GAIN trimpot (R13) for 4.50 VDC on the output.
Output voltage is now scaled for 20 mV per millimeter of
water depth in the measuring tube which equals 100 mV
per millimeter of precipitation.
2.2.5 CHECK OUTPUT LINEARITY
a) Pour water slowly into catchment funnel until unit self
siphons.
b) Add 50 ml of water and observe output voltage.
c) The output voltage is calculated using the ratio of 500
mV per 50 ml. Gauge accuracy is specified as ± 1 mm of
collected precipitation. Measured output voltage should
be within ± 100 mV of the calculated value.
d) Continue adding water in 50 ml increments and observing
voltage output until measuring tube is full at 500 ml total
volume. Measured output voltage should be within ± 100
mV of the calculated value at each 50 ml increment.