INTRODUCTION
The Cla-Val Model 81-01/681-01 Check Valve is an automatic
valve designed to close drip tight when outlet pressure exceeds
inlet pressure. It is a hydraulically operated, pilot controlled,
diaphragm type globe or angle valve. In operation higher outlet
pressure is directed into the cover of the valve through the control
tube line and the valve closes tight. When inlet pressure exceeds
the outlet pressure the disc lifts from the seat as fluid in the cover
chamber is expelled into discharge end of the valve causing the
valve to open.
INSTALLATION
1. Allow sufficient room around the valve to make adjustments and
for disassembly.
2. It is recommended that gate or block valves be installed on both
ends of the 81-01/681-01 to facilitate isolating the valve for preven-
tive maintenance.
NOTE: BEFORE VALVE IS INSTALLED, PIPE LINES SHOULD
BE FLUSHED OF ALL CHIPS, SCALE, AND FOREIGN MATTER.
3. Place the valve in the line with flow through the valve in the
direction indicated on the inlet nameplate 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.
4. Cla-Val Valves operate with maximum efficiency when mounted
in horizontal piping with the cover UP; however, other positions are
acceptable. Due to size and weight of cover and internal compo-
nents of six inch valves and larger, installation with the cover up is
advisable. This makes periodic 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. A Cla-Val X101 Valve Position Indicator may be installed in the
cover center port to provide a visual indication of the stem
position during start-up.
2. Slowly open the gate or block valves on both ends of the Cla-
Val Check Valve. Carefully loosen the center cover plug of the
Hytrol Valve, or the vent valve of X101 Valve Position Indicator (if
installed), and bleed air from valve. Retighten cover plug or vent
valve after all air is expelled.
3.To check the operation of the valve, lower the pressure at the valve
inlet and the valve will close. Return the inlet pressure to a higher
pressure than the outlet pressure and the valve will open.
MAINTENANCE
1.Cla-Val Valves require no lubrication or packing and a minimum of
maintenance. However, a periodic inspection schedule should be
established to determine how the fluid handled is affecting the
efficiency of the valve assembly. Minimum of once per year.
2. Repair and maintenance procedures of the Cla-Val Hytrol valve
and 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. 3/8”, 1/2” and 3/4” size Cla-Val Model 81-01/681-01 Check
Valves are internally ported for control fluid flow. After servicing
these valves be sure that small hole in body, diaphragm and cover
line up together.
4. When ordering parts always refer to the catalog number and
stock number on the valve nameplate.
MODEL
INSTALLATION / OPERATION / MAINTENANCE
81-01/681-01
Check Valve
Fails to close
Fails to open
(Valve is
designed to
fail closed
on a
diaphragm
failure)
Lack of cover chamber
pressure
Diaphragm damaged
Diaphragm assembly
inoperative. Corrosion
or excessive scale build
up on valve stem
Mechanical obstruction
Object lodged in valve
Worn disc
Badly scored seat
Insufficient line pressure
Diaphragm assembly
inoperative Corrosion
on valve stem
Diaphragm damaged
Check upstream and
downstream pressure,
tubing for restrictions
Replace diaphragm
Clean and polish stem
Replace any defective
part damaged, badly
eroded
Remove obstruction
Replace disc
Replace seat
Check pressure
Clean and polish stem
Replace any defective
part damaged, badly
eroded
Replace Diaphragm
SYMPTOM PROBABLE CAUSE REMEDY
