National Weather Service
Fischer-
Porter
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Overview
Equipment
Site Prep
F&P
GMA
DCOM
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DATA
Video
1. Precipitation Gauge Preparation

Process and annotate any existing paper tape record prior to beginning this procedure.

1.1  Remove the Fischer & Porter (FP) gauge housings and bucket.

1.2  Empty and dry the bucket.

1.3  Disconnect and remove the battery. Package and retain the battery for short term storage at the supporting WFO.

1.4  Remove the solar panel and piping mount; clean out threads and threaded hole in base. Package and retain the solar panel for short term storage at the supporting WFO.

1.5  Remove internal wiring, clamps, and terminal strip(s).

1.6  Loosen the two 7/16" bolts holding the punch assembly.

1.7  Remove the small slotted screw, releasing the eyelet end of the wound cable from the front support arm assembly.

1.8  Replace the small slotted screw.

1.9  Unhook the tension spring from the front support arm assembly.

1.10  Remove the punch assembly; tighten the two 7/16" bolts loosened in step 5.

1.11  Raise the front support arm assembly with shipping bolt so that the dash pot piston is near the top of travel.

1.12  Unscrew the zero adjust knob.

1.13  Remove the two helical main springs, hook, and zero adjust knob.

1.14  Remove the two screws holding the pointer and remove the pointer. Replace the screws.

1.15  Remove the tape spool assembly; replace screws.

1.16  Remove the dash pot and piston. Do NOT replace screws.

1.17  Remove the gasket and clean oil off all surfaces.

1.18  Dispose of oil in accordance with local environmental regulations.

1.19  Check all flexures. Replace any that are bent, kinked, cracked, or broken.

[M WYATT WILL PROVIDE FLEXURE PROCEDURE TO BE INSERTED HERE]

IMPORTANT!  All flexures must be flat and in good condition and all flexure mounting screws must be tight to ensure proper operation with the Load cell.

1.20 Package removed tape punch mechanism components for short term storage at the supporting WFO


2. Install the Load Cell Assembly

NOTE: The load cell assembly is installed inside the FP gauge. All the equipment that interfaces to the FP gauge is mounted to existing threaded holes.

2.1 Unpack the GMA enclosure container.

2.2 Open the GMA enclosure; retrieve the small box within.

2.3 Find the padded envelope containing the load cell assembly.

CAUTION
Use care when handling the load cell assembly. Do not scratch the surface of the load cell. The ball must be present on the free end of the Load cell.

2.4  Find the envelope with four long 4-40 Allen head screws and washers. Place the washers on the screws with a lock washer sandwiched between the flat washer and the head of each screw.

2.5  Using a short individual Allen wrench and the long screws, install the load cell assembly where the dash pot was mounted. Finger tighten. The ball should be visible through the hole.

NOTE: The printed circuit board on the load cell assembly should face the door of the gauge.

2.6  Apply anti-seize compound to the threads and install the plunger in the dash pot piston hole on the bottom of the front support arm assembly. Finger tighten. Do NOT use a wrench..

2.7  Ensure that the plunger is centered in the hole, then lower the shipping bolt until the plunger is near the ball. If adjustment is necessary, loosen the four scale support mounting bolts; re-tighten after adjustment.

Leave the front support arm supported on the shipping bolt until requested to lower it onto the ball in the Load Cell Calibration Procedure (Step 6, Procedure 7).

2.8  Find the load cell cable.

2.9  Feed the white plastic connector through the threaded inlet in the base of the gauge; plug it into the load cell connector. It is keyed and only fits easily when inserted the correct way. The retaining clip should snap when fully seated.

 

2.10  Separate the strain relief into its two parts; screw the coupler into the threaded inlet in the gauge base until fully seated.

2.11  Adjust the cable to leave a little slack inside the gauge; screw the spring part of the strain relief onto the coupler until the cable is captured (about fully seated).