Sierra 840 User Manual

Chapter 5 Troubleshooting

Series 830/840/860 Instruction Manual

5-2

IM-83/84/86-H

Flow Meters and Flow Controllers with Electromagnetic Valves

Problem

Possible Cause

Solution

No output

Clogged sensor

PCB defective

Inlet filter screen clogged

Clean or replace sensor

Repair or replace PCB

Clean or replace screen

Unit will not zero

Gas leak

Application requires high pressure and
non-horizontal mounting

PCB defective

Find and correct leaks

Re-zero transducer

Repair or replace PCB

Controller does not
respond to set point

Low or no gas pressure

Faulty cable or connector

Set point is below 2% of full scale

Set correct gas pressure

Correct or replace

Increase set point or disable auto
shut off circuit

Flow does not match set point

No gas pressure

Inlet filter screen clogged

Out of adjustment

Set correct gas pressure

Clean or replace

Adjust R22 balance on 840 models,
consult factory for others

Reads full scale with no flow
or with valve shut

Defective sensor

Gas leak

Return to factory for replacement

Find and correct leaks

Out of calibration

Dirty or clogged sensor

Change in composition of gas

Gas leak

PCB defective

LFE dirty

Inlet filter screen clogged

Incorrect inlet conditions (high flow and
NPT models)

Clean or replace sensor

See K-factory tables

Find and correct leaks

Repair or replace PCB

Clean LFE

Clean or replace screen

Re-plumb transducer correctly