CLA-VAL 750-20, Установка, эксплуатация и обслуживание, Страница: 20 / 23

CLA-VAL
Copyright Cla-Val 2018 Printed in USA Specifications subject to change without notice.
1701 Placentia Ave • Costa Mesa CA 92627 Phone: 949-722-4800 • Fax: 949-548-5441 • E-mail: info@cla-val.com • www.cla-val.com
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INSTALLATION / OPERATION / MAINTENANCE
Flow Control
CV
MODEL
N-CV (R-06/2018)
DESCRIPTION
The CV Control is an adjustable restriction which acts as a
needle valve when flow is in the direction of the stem. When
flow is in the reverse direction, the port area opens fully to
allow unrestricted flow. When installed in the control system of
a Cla-Val automatic valve, it can be arranged to function as
either an opening or closing speed control.
OPERATION
The CV Flow Control permits full flow from port A to B, and
restricted flow in the reverse direction. Flow from port A to B
lifts the disc from seat, permitting full flow. Flow in the reverse
direction seats the disc, causing fluid to pass through the clear-
ance between the stem and the disc. This clearance can be
increased, thereby increasing the restricted flow, by screwing
the stem out, or counter-clockwise. Turning the stem in, or
clockwise reduces the clearance between the stem and the
disc, thereby reducing the restricted flow.’
INSTALLATION
Install the CV Flow Control as shown in the valve schematic
All connections must be tight to prevent leakage.
DISASSEMBLY
Follow the sequence of the item numbers assigned to the
parts in the cross sectional illustration for recommended
order of disassembly.
Use a scriber, or similar sharp-pointed tool to remove O-ring
from the stem.
INSPECTION
Inspect all threads for damage or evidence of cross-
threading. Check mating surface of seat and valve disc for
excessive scoring or embedded foreign particles. Check
spring for visible distortion, cracks and breaks. Inspect all
parts for damage, corrosion and cleanliness.
CLEANING
After disassembly and inspection, cleaning of the parts can
begin. Water service usually will produce mineral or lime
deposits on metal parts in contact with water. These
deposits can be cleaned by dipping the parts in a 5-percent
muriatic acid solution just long enough for deposits to dis-
solve. This will remove most of the common types of
deposits. Caution: use extreme care when handling
acid. If the deposit is not removed by acid, then a fine grit
(400) wet or dry sandpaper can be used with water. Rinse
parts in water before handling. An appropriate solvent can
clean parts used in fueling service. Dry with compressed air
or a clean, lint-free cloth. Protect from damage and dust
until reassembled.
REPAIR AND REPLACEMENT
Minor nicks and scratches may be polished out using a fine
grade of emery or crocus cloth; replace parts if scratches
cannot be removed.
Replace O-ring packing and gasket each time CV Flow
Control is overhauled.
Replace all parts which are defective. Replace any parts
which create the slightest doubt that they will not afford com-
pletely satisfactory operation. Use Inspection steps as a
guide.
REASSEMBLY
Reassembly is the reverse of disassembly; no special tools
are required.
TEST PROCEDURE
No testing of the flow Control is required prior to reassembly
to the pilot control system on Cla-Val Main Valve.