Cla-Val 90-48/690-48 Quick Manual - Manual

SYMPTOM PROBABLE CAUSE REMEDY
Main valve No pressure at valve inlet Check inlet pressure
fails to open
Main valve diaphragm assembly Disassemble, clean and polish
inoperative stem, replace detective parts
Pilot Valve (CRD) not opening:
1. No spring compression
1. Tighten adjusting screw
2. Damaged spring 2. Disassemble and replace
3.Spring guide not in place 3. Assemble properly
4. Yoke dragging on inlet nozzle 4. Assemble properly
Flow Control (CV) disc inoperative. Disassemble, clean and polish
corrosion or excessive scale
stem. Replace worn parts
buildup on stem
Main valve Foreign matter between disc and Disassemble main valve, remove
fails to close seat or worn disc. Scale on stem matter, clean parts and replace
or diaphragm ruptured defective parts
Flow Clean Strainer plugged Remove and clean or replace
CK2 (isolation valves) closed Open isolation valves
Pilot Valve (CRD) remains open:
1.Spring compressed solid
1. Back off adjusting screw
2.Mechanical obstruction 2. Disassemble and remove
obstruction
3.Worn disc 3. Disassemble remove and
replace disc retainer assembly
4.Yoke dragging on inlet nozzle 4. Assemble properly
diaphragm nut
5.Diaphragm damaged or loose 5. Disassemble. replace
diaphragm nut. Leakage from diaphragm and/or tighten nut
vent hole in cover
Fails to Air in main valve cover and/or Loosen top cover plug and
regulate tubing fittings and bleed air
Pilot Valve (CRD) yoke dragging Assemble properly
on inlet nozzle
Pilot Valve (CRD) spring not
Check outlet pressure
in correct range to control requirements and compare
existing spring with Spring Chart
The Cla-val Model 90-48 Pressure Reducing Valve with Low Flow By-Pass
automatically reduces a higher inlet pressure to a steady lower downstream
pressure regardless of changing flow rate. The pressure reducing valve is
hydraulically operated and controlled by a CRD pilot control, which senses
pressure at the main valve outlet. An increase in outlet pressure forces the
CRD pilot control to close and a decrease in outlet pressure opens the control.
This causes the main valve cover pressure to vary, modulating the main valve
and thereby maintaining constant outlet pressure. The control system is very
sensitive to slight pressure changes and immediately controls the main
valve to maintain the desired downstream pressure. Pressure setting
adjustment is made with a single adjusting screw
INSTALLATION
1. Allow sufficient room around the valve assembly to make adjustments
and for servicing.
2. lt is recommended that gate or line block valves be installed on both
ends of the 90-48/690-48 valve assembly to facilitate isolating the valve for
maintenance. Minimum one pipe diameter apart.
NOTE: BEFORE THE VALVE IS INSTALLED, PIPE LINES SHOULD BE
FLUSHED OF ALL CHIPS, SCALE, AND FOREIGN MATTER.
3. Place the valve assembly in the line with flow through the valve in the
direction indicated on the inlet plate or by flow arrows. Check all fittings
and hardware for proper makeup and that no apparent damage is evident.
Be sure main valve cover nuts/bolts are tight. Pressure in some applications
can be very high so be thorough in checking and inspecting for proper
installation and makeup.
4.Cla-Val Valves operate with maximum efficiency when mounted in hor-
izontal piping with the cover UP: however, other positions are acceptable.
Due to size and weight of cover and internal components of six inch and
larger valves, installation with the cover up is advisable. This makes period-
ic inspection of internal parts readily accessible.
5.
Caution must be taken in the installation of this valve to insure that
galvanic and/or electrolytic action does not take place. The proper use
of dielectric fittings and gaskets are required in all systems using dis-
similar metals.
OPERATION AND START-UP
1. Prior to pressurizing the valve assembly make sure the necessary
gauges to measure pressure in the system are installed as required by the
system engineer. A Cla-Val X101 Valve Position Indicator may be installed
in the center cover port to provide a visual indication of the valve movement
during startup.
CAUTION: During start-up and test procedures a large volume of water
may be discharged downstream. Check that the downstream venting is
adequate to prevent damage to personnel and equipment. All adjustments
in pressure should be made slowly while under flowing conditions.
If the main valve closes too fast it may cause surging in upstream piping.
2.
If isolation valves (B) are installed in pilot system open these
valves (see schematic).
3. Optional Cla-Val CV Flow Controls (C or S) provide adjustable regula-
tion of flow in and out of the main valve chamber to minimize pulsations
that sometime occur at very low flow rates. If CV Controls are installed,
loosen jam nut and turn adjustment screw counterclockwise from closed
position 3.5 turns for an initial setting.
4. Open the upstream gate or block valve just slightly to allow the main
valve assembly and pilot system to fill with liquid. Downstream gate or
block valve must be closed.
5. Carefully loosen tube fittings at highest points and bleed air from pilot
control system. Carefully loosen the plug at top of main valve cover to
bleed air from cover. If an indicator is installed, carefully loosen the air
bleed valve at top of indicator. Tighten tube fittings.
6. Open the upstream gate or block valve fully.
7. Slowly open the downstream gate or block valve. Flow should occur
and pressure should remain constant.
8. Adjust the Pilot Controls to desired pressure. To change pressure setting,
turn the adjusting screw clockwise to increase pressure, counterclock-
wise to decrease pressure. There must be liquid flowing through the valve
during pressure adjustments. When the desired setting has been made,
tighten jam nut and replace CRD cover. Low flow by-pass control (4) must
be set higher (minimum 5 psi) than main CRD (3).
9. To check the operation of the valve, open and close the downstream
gate valve. The downstream pressure should remain constant.
10. If opening and closing speed controls (C or S) are installed in the valve
pilot system, fine tune the opening and closing speed of the main valve
while performing step 9. Turn the CV adjustment screw clockwise on the
opening speed control to make the main valve open slower. Turn the
adjustment screw clockwise on the closing speed control to make the
main valve close slower. When adjustments have been completed
tighten jam nuts.
MAINTENANCE
1. Cla-Val Valves and Controls require no lubrication or packing and a
minimum of maintenance. However, a periodic inspection schedule should
be established. Minimum of once per year.
2. Repair and maintenance procedures of the Cla-Val Hytrol Main Valve
and pilot control components are included in a more detailed IOM manual.
It can be downloaded from our web site (www.cla-val.com) or obtained by
contacting a Cla-Val Regional Sales Office.
3. When ordering parts always refer to the catalog number and stock
number on the valve nameplate.
Pressure Reducing Valve with Low Flow By-Pass
90-48/690-48
MODEL
INSTALLATION / OPERATION / MAINTENANCE