Xylem H-340-CalKit - Manual (Page 4)

1-2 Instruction Manual
H-340-CalKit
Using the Rain Gauge Calibration Kit
The H-340-CalKit is designed to be used either with or without the H-340's funnel cover installed.
To allow for visibility of the bucket mechanism during calibration we recommend calibrating with
the funnel cover removed. Use the special brush included with the CalKit to clean the water
bottle orifice. Do not attempt to clean the orifice with a wire or needle, as the orifice is easily
damaged. Use fresh clean water for the test.
Begin by cleaning any algae, debris or hard water deposits from the bucket mechanism.
Push a 24-inch hose over each drain port. Place the rain gauge where the exiting water can be
collected into the two 250ml graduated cylinders. Adjust the leveling feet until the bubble in the
bulls-eye level is exactly centered.
Fill one of the 250ml graduated cylinders with 198.0ml of
water. Unscrew the orifice cap from the water bottle. With
the valve on the bottle closed pour the measured water into
the bottle. Screw the orifice cap onto the bottle making
sure it is securely tightened. With the valve still closed
invert the bottle and pace it on top of the rain gauge as
shown. The vacuum formed by the closed valve keeps the
water from running out of the bottle. Place the graduated
cylinders under each drain hose to capture all water as it
exits the rain gauge. Open the valve on top of the water
bottle to start the flow of water through the rain gauge.
Carefully count the number of bucket tips until the water is
completely drained from the bottle. The bucket should tip
24 times, leaving the 25th bucket less than 1/3 full.
Manually dump the little remaining water in the 25th
bucket. The water in the two graduated cylinders should be
equal. If either the number of tips is not 24 or the water
volume in the two cylinders are not equal, make the proper
adjustments as described below and re-verify the calibration.
This procedure may need to be repeated several times
before proper calibration is obtained.
Adjusting the Tipping Bucket Mechanism
Warning: DO NOT ADJUST THE BUCKET STOPS. Do not adjust the bucket stops in an
attempt to balance the bucket mechanism. Instead, the H-340 has an adjusting screw above the
buckets by which the two buckets can be balanced. This eliminates the need to adjust the stops to
compensate for any inequality of weight due to manufacture and assembly. The bucket stops are
set at the factory to give equal travel to each bucket as the knife edge divider passes under the
water flow. Changing or adjusting the stop post height causes a false reading of equal amounts of
water in each bucket. This is due to the unequal distance the bucket center must travel from side