Cashco 1078 User Manual
INSTALLATION, OPERATION AND MAINTENANCE MANUAL (IOM)
Vacu-Gard Pilot Operated Blanketing Valve
I. DESCRIPTION AND SCOPE
IOM-1078
09-10
Model 1078
SECTION I
The Model 1078 Vacu-Gard is a pilot operated
blanketing valve intended for installation on top of
medium to large storage tanks. The standard valve
comes with either FNPT or Weldneck connections.
SECTION II
II. PRIOR TO INSTALLATION
Clean out blanket gas supply lines prior to valve
installation to get rid of dirt, sand, loose scales and
other foreign particles trapped in the piping. This is
particularly true for new tanks and/or new piping. One
way to accomplish this is to blow out the lines from the
supply side up to the connection to the Vacu-Gard inlet.
SECTION III
III. INSTALLATION
It is always good practice to install a main line fi lter
upstream of any tank blanketing valve. The element
should be approximately 5-40 microns with a fl ow ca-
pacity at least equal to or greater than that of the VacuGard.
The valve should be installed in the normal upright
position. The inlet is horizontal and the outlet is vertical downward. There is an optional horizontal outlet
available only for the remote sensing design. All outlet
piping from the valve body to the vessel must be at
least as large or larger than the outlet port in the body.
Keep piping as short as possible for best valve performance.
All standard 1” size valve bodies are cast 316 stainless
steel (CF3M). Standard 2” size valve bodies are
available in cast carbon steel (WCB) or stainless steel
(CF3M). All sizes have 316 SST Trim.
CAUTION
Follow your company’s safety procedures to avoid
injury to personnel or damage to equipment.
For Remote Sensing:
The sense line should be a 1/2” O.D. tube (or larger)
and the length should not exceed fi fteen feet. Longer
lengths may be used with larger diameter sense lines.
The sense line should slope downward from the pilot to
the tank to allow condensate, if any, to drain back into
the tank. (The sense port is the port on the side of the
pilot body marked with an “S”. A “tee” may be added to
the sense port for gauging pressure in the vessel.)
For Dip-Tube Sensing:
The integral dip-tube line must protrude into the tank at
least 6” below the roof.
NOTE: The port at the end of the main valve body opposite the inlet is not a sense port. This port is an optional horizontal outlet for remote sensing valve. This
port should not be used for pressure gauging since the
pressure at this point may be higher than the maximum
tank pressure and may cause damage to the gauge.
NOTE: The sense chamber is not a dead-ended cham-
ber. In addition to the main fl ow and pilot fl ow when the
valve is open, there is also a very small fl ow from the
pilot valve into the vessel through the sense connec-
tion. Therefore the sense tube must be large enough
so that the fl ow will not be restricted. Premature closing
of the valve may occur if excess pressure builds up in
the sense chamber due to a sense line that is too small.
CAUTION
A pressure/vacuum relieving device large enough to
vent excess pressure and to serve as an emergency
vacuum breaker must be installed to protect the tank.
SECTION IV
IV. START-UP
Operation of the Model 1078 is automatic once the set
pressure has been established. (The set pressure is
usually bench-set at the factory prior to shipment.) The
set pressure may be approximated on the bench or set
after the valve has been installed. If the set pressure is
to be made after valve installation, the adjusting screw
should be backed off before applying inlet pressure to
the valve. NOTE: The set pressure is defi ned as the
pressure at which the valve should be fully closed on
increasing tank pressure.
Refer to applicable drawing dependent on sensing
style. Temporarily keep valve A closed. Use an
appropriate pressure indicating instrument for G2
to measure the pressure in the vessel. (For external
sensing open valves C and E, then valve B.) Now very
slowly open valve A while watching gauge G2. NEVER
SLAM OPEN VALVE A! The Vacu-Gard should close
when the tank pressure reaches the set pressure of the
pilot. To adjust the set pressure, remove the hex cap
at the top of the valve and loosen the jam nut around
the adjusting screw. Clockwise rotation of the adjusting
CAUTION
DO NOT overtighten threaded connections since damage or breakage may result. Wrap all NPT threads with
TFE tape. Apply anti-seize compound on bolt threads.
screw will increase the set pressure. Counter clockwise
will decrease the pressure provided there is a manual
valve to vent the excess pressure. Do not set the set
pressure beyond the nameplate range. Tighten the jam
nut after adjustments are made and replace the hex
cap.
CAUTION
DO NOT exceed the maximum inlet pressure on the
nameplate, as the valve may not open in time. Likewise, the minimum nameplate pressure must be maintained, otherwise the valve may not open.
In the event that the adjusting screw is backed out
eliminating the spring compression, intentionally or
unintentionally, the valve will begin to open when the
tank pressure reaches about 1” w.c. vacuum.
VACUUM SET VALVES: For valves that are set to
open and close on vacuum - a clockwise rotation of
the adjusting screw will set the valve to open closer
towards atmospheric pressure (less vacuum).
SECTION V
V. SHUT-DOWN
To shutdown the Vacu-Gard, reverse start-up procedure and bleed off trapped pressure before disassembly.
2 IOM-1078
Normal Installation - Remote Sensing
Model 1078 Pilot Operated Vacu-Gard
Installation - with Integral Dip-Tube Sensing
Model 1078 Pilot Operated Vacu-Gard
3IOM-1078
SECTION VI
VI. MAINTENANCE
The Model 1078 should be periodically actuated and
all sliding surfaces and seals lubricated to ensure
smoothness of operation. The frequency required
depends on the severity of the service conditions. At
least once a year is recommended.
CAUTION
If the valve must be disassembled for any reason,
fi rst make sure all pressure to the blanketing valve is
blocked and any pressure trapped in the valve is vented safely out. Refer to your company procedure for
any special precautions when handling toxic or other
hazardous materials.
Refer to the appropriate drawings for disassembly.
Pilot Internals: NOTE: The working components and
o-rings within the pilot body may be inspected and
replaced without the need to take apart the diaphragm
case. To remove the body internals, simply remove the
tubings (115) and unscrew the pilot body (038) from
the pilot mount (037)(on 1” valve) or from the pilot
connector (047)(on 2” valve). NOTE: Be careful not
to drop internal components. The return spring (025)
could dislodge the spindle (020) as the body and pilot
mount separate.
CAUTION
If the piston (107) does not remain in the main body
cavity, it may slowly slide out from the housing. Make
sure the piston does not fall out of the housing while
retracting the housing from the main body.
mount (037) upwards to remove from the main body.
The piston (107) and other internal parts should come
out with the pilot mount. To access the o-rings (105,
106), pull the piston (107) out of the pilot mount and
remove the screw (111) and lock washer (112). The
fl ow plug (109) will come out with a straight pull.
2” SIZE VALVES: Remove the six cap screw (129)
and lock washers (130) holding the piston housing (124)
to the main body. Carefully lift the pilot housing (124)
upwards to remove from the main body. To access
the o-rings (105,106), pull the piston (107) out of the
piston housing or remove it from the main body cavity.
Remove cap screw (011) and lock washer (012). The
fl ow plug (109) will come out with a straight pull.
To access seat ring seal (132), remove cap screws
(011) and lock washers (012) from seat ring (131).
Remove the seat ring from the main body. If the seat
ring is diffi cult to remove, thread two cap screws into
the threaded holes and remove the seat ring by lifting
upwards on the cap screws.
To Disassemble the Diaphragm Case Assembly:
Relax the compression on spring (007) by fi rst
unscrewing the cap (001). Rotate the jam nut (003)
CCW two rotations and then back out the adjusting
screw (002). Remove nuts (015), lock washers (012),
fl at washers (041) and cap screws (011) from around
the diaphragm case (009). Lift up to remove upper case
assembly, ring gasket (014) and diaphragm assembly.
Remove cap screws (011) and lock washers (012) from
the upper and lower cases to replace gaskets (008).
At re-assembly torque cap screws 13-15 ft-lbs.
To Disassemble Pilot Diaphragm Assembly:
Secure head of center bolt (017) in soft jawed vise.
Rotate nut (015) CCW. Remove nut, fl at washers (033)
and lock washer (012). Lift up to remove upper support
plate (016), gasket (018) and diaphragm (013). Lift up
to remove lower support plate (016) and gasket (018).
To Disassemble the Main Valve Assembly:
1” SIZE VALVES: Remove the four cap screws
(011) and washers (012, 041) holding the mounting
plate (036) to the main body. Carefully lift the pilot
Replace all parts that show signs of damage or excessive
wear. Make sure the material for new parts is suitable
for the service, especially elastomeric components.
If an o-ring needs to be replaced, be sure to use the
correct size and material. Prior to reassembly, make
sure all parts are clean and free of contamination and
seating surface is free of scratches.
CAUTION
DO NOT overtighten threaded connections since damage or breakage may result. Wrap all NPT threads with
TFE tape. Apply anti-seize compound on bolt threads.
Very lightly lubricate all o-rings with a lubricant that is
compatible with the service, sealing surfaces of gaskets and diaphragms also.
Reassemble in reverse order - utilize specifi c
instructions as follows for:
DIAPHRAGM CASE ASSEMBLY: Ensure center
bolt (017) is installed with the threaded end up. Install
one bolt gasket (018) between the center bolt and the
lower support plate (016) as shown on the drawing. An
identical gasket is used between the upper surface of
the sense diaphragm (013) and the bottom side of the
upper support plate. This is to ensure a tight squeeze
4 IOM-1078
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