BRONKHORST HIGH-TECH B.V.
9.17.044
page 17
4 MAINTENANCE
4.1 General
No routine maintenance is required to be performed on the meters or controllers. In case of severe
contamination it may be required to clean the valve orifice separately.
4.2 LIQUI-FLOW L30 sensor
The user cannot change the flow range of a liquid flow sensor. The sensor is an integral part of the
instrument and cannot be removed from it. For occasional cleaning the instrument may be flushed with a
cleaning fluid.
4.3 Controllers
All sensor types can be combined with a control valve to be operated together as a control loop. Controller
systems are either available as separate units; a sensor and a control valve, or as an integrated unit.
If applicable maintenance procedures are described under “control valves”
4.4 Control
valves
Control valves cannot be used for shut-off and/or on-off applications. Pressure surges, as may occur during
system pressurisation or deflation must be avoided.
4.4.1 Solenoid
valves
These are considered to be the directly operated control and pilot valves. They can be disassembled in the
field by the user for cleaning and servicing. The parts can be cleaned with a cleaning liquid, or in an ultrasonic
bath.
To disassemble the valve proceed as follows:
a)
disconnect the instrument connector (not necessary with separate valve)
b)
remove the hex nut on top of the valve assembly
c)
lift the cover (coil) assembly
d)
unscrew the flange
e)
lift valve assembly carefully from the base
f)
unscrew set screw for the orifice and subsequently loosen the orifice and the orifice holder
g)
remove the plunger assembly
Clean parts and carefully re-assemble in reverse order. It is recommended to replace the O-rings prior to re-
assembly.
After having re-assembled the control valve, it is recommended to check the control characteristics of the
valve. This can best be done by using a separate variable 15 Vdc power supply source.
Proceed as follows:
-
disconnect the valve leads and connect to supply source
-
apply gas pressure as per working conditions
-
apply power by gradually increasing voltage
-
the valve should open at 7 Vdc
±
3 Vdc
-
the fully opened position is reached at approx. 9 Vdc
±
1.5 Vdc.
In case the valve does not operate within the voltage levels stated, then it must be disassembled, and the
orifice must be adjusted to the proper position.
Re-assemble valve and repeat procedure if required.
