Check the operation of the reed switch by:
Remove the reed switch assembly from the meter and
connect a battery ohm meter.
Pass a normal
magnet across of the reed switch and if the
resistance changes from at least I mega ohm to less than I ohm
due to the movement of the magnet, the reed switch is
operative.
To check that the piston is rotating whilst liquid is flowing:
1)
Hold an ordinary magnetic compass near the reed switch
recess in the meter body. If the needle oscillates wildly the
piston is moving.
2)
A visual ( check can be made on the quantity of liquid
flowing through the system with the control device fully
open. If the
flow rate is drastically below
that normally
delivered the piston could be stationary and helping to
produce a prohibitive
head loss across the meter.
3)
Adjust the system flow rate to its maximum and check for
a slight vibration of the meter caused by a rotating piston. If
all the previously mentioned checks prove satisfactory then
the meter must be removed front the line and dismantled and
inspected as detailed in maintenance sections.
Possible causes of imperfect operation are:
1)
A fractured piston allowing the passing of unmetered
fluid.
2)
Resistance to motion of the piston due to:
- Particles of foreign matter embedded in the working
surfaces of the meter.
- A
"
gummed up
"
meter due to ineffective
temperature control or. settling out during
"
shut o r .
- A distorted piston due to operation at
temperatures in excess of the maximum allow .
- Worn barrier or rollers allowing the piston to "cock"
during operation are not in the right position.
-
Bent
piston pegs due to excessive pressure drop
across the meter.
Pag.11
