Flow Safe F70VP Series Instruction manual

High Performance Safety Relief Valves
INSTALLATION,
OPERATION, & MAINTENANCE MANUAL
Revision: B
Date of Issue: Oct. 2, 2015
Approved by: GG jwo
Project Engineer Engineering Projects Director
F70VP SERIES
VACUUM
RELIEF VALVE

INSTALLATION, OPERATION, &
MAINTENANCE MANUAL
TITLE: F70VP Series Rev. B
Vacuu Relief Valve Page 2 of 20
TABLE OF CONTENTS
Topic Page
1.0 General ................................................................................................ 3
2.0 Description, Operation, Service Envelope, Installation, & Startup
2.1 Description / Operation ........................................................................ 4
2.2 Service Envelope ................................................................................. 5
2.3 Installation............................................................................................ 6
2.4 Startup ................................................................................................. 6
3.0 Main Valve Maintenance
3.1 Disassembly of the F70VP Series Main Valve ..................................... 7
3.2 Reassembly of the F70VP Series Main Valve...................................... 10
4.0 Pilot Valve Maintenance
4.1 F100 Pilot Valve (High pressure: 2 – 14.6 psi vac) ............................. 11
4.2 F100 Pilot Valve (Low pressure: 0.36 – 5 psi vac) .............................. 13
5.0 Pilot Valve Set Pressure Adjustment ................................................... 15
6.0 Final Assembly Testing........................................................................ 16
7.0 Troubleshooting Guide .......................................... .............................. 18
8.0 Softgoods Kits .......................................... ........................................... 19

INSTALLATION, OPERATION, &
MAINTENANCE MANUAL
TITLE: F70VP Series Rev. B
Vacuu Relief Valve Page 3 of 20
1.0 GENERAL
1) This manual is intended to provide users with direction and guidance for the maintenance of
FLOW SAFE F70VP Series vacuum relief valves. This manual indicates the proper method of
valve disassembly, soft goods replacement, and valve reassembly. FLOW SAFE provides this
manual as a guideline and reference only. It is not intended to serve as a training manual or
manufacturing guide. FLOW SAFE assumes no responsibility for personal or property damage
that may occur in conjunction with this manual.
2) FLOW SAFE recommends that all valves be placed on a regular maintenance schedule that
includes the routine replacement of softgoods. FLOW SAFE recommends softgoods
replacement every three years but cautions that each customer make their own determination
and set their own schedule based upon use and environment. FLOW SAFE believes that when
maintenance and reassembly is performed as outlined in this manual there is no safety hazard.
Cycling the valve at least once a year is considered to be good practice to verify operation.
3) When a new valve leaves FLOW SAFE, it has been manufactured and tested by trained and
experienced personnel. When you remove a valve from your system and perform the
maintenance tasks that are outlined herein you will need proper training.
Do not attempt to accomplish these tasks without adequate training and understanding of the
valve operation.
4) Any and all stated or implied warranties that are in effect during the purchase of a new FLOW
SAFE valve are null and void once the valve has been disassembled by someone other than
approved FLOW SAFE personnel.
5) It is highly recommended that all instructions herein be read in full prior to any assembly,
disassembly, or operation of this equipment.
6) Specific design details described in this document are subject to change without notice.
7) Should the need arise for general assistance, contact the FLOW SAFE Sales department at (716)
662-2585 or [phone]. For more detailed technical assistance, contact the FLOW SAFE
Engineering department at [phone].

INSTALLATION, OPERATION, &
MAINTENANCE MANUAL
TITLE: F70VP Series Rev. B
Vacuu Relief Valve Page 4 of 20
2.0 DESCRIPTION, OPERATION, SERVICE ENVELOPE, INSTALLATION, and STARTUP
2.1 DESCRIPTION / OPERATION
The FLOW SAFE F70VP Series vacuum relief valve provides vacuum protection with the ability to handle
large volumes and provide consistent, leak-tight seating. This valve is a variation of the F70PR Series or
F7000 pilot-operated relief valve, and is also intended for installations where ASME Code construction is
not required. Standard construction of the main valve assembly includes threaded (in the 1 x 2 and 1-1/2
x 2 size) or ANSI 150# flanged connections.
The F70VP uses a piston in the main valve that will open under a design vacuum level. The assembly
uses a modulating, flowing pilot valve (Model F100) to control piston movement at certain vacuum levels.
System vacuum is present below the main valve seat, while atmospheric pressure is routed through the
pilot valve and to the dome cavity of the main valve. At the designated vacuum set pressure, the pilot
allows dome pressure to be drawn down to a vacuum state proportionally to demand at set pressure.
The net positive upward force on the piston exerted by atmospheric pressure in the main valve outlet
allows the piston to lift. Once the system vacuum condition is relieved, the pilot valve closes, which
allows the dome to repressurize and main valve piston to close. When closed, atmospheric pressure
exposed to the top of the piston counteracts system vacuum beneath the piston seat, creating a
downward force to seat the piston. The pilot valve is leak-tight to approximately 95% of vacuum set
pressure.
When furnished without a pilot, the F70VP relief valve relies on piston weight alone to open at the
vacuum set point desired. Operation is the same as described herein, except that set pressure is fixed.
In addition, the valve may be configured to handle a vacuum process connection at the side flange, with
atmospheric inlet below the main seat. Contact Flow Safe for availability of specific vacuum set
pressures and valve configurations.

INSTALLATION, OPERATION, &
MAINTENANCE MANUAL
TITLE: F70VP Series Rev. B
Vacuu Relief Valve Page 5 of 20
For systems that normally operate on positive gage pressure, the F70VP pilot tubing must be fitted with
backflow preventer check valves to keep the main valve closed when not under vacuum. A typical
arrangement is shown below:
2.2 SERVICE ENVELOPE
(1) Confirm low-temperature environmental applications with factory.
(2) Ratings based on use as low-pressure seat in 1-1/2 x 2, 2 x 3, and 3 x 4 only
(3) “PSI VAC” as used in this document is equivalent to “negative” gage pressure;
for example, 5 psi vac is approximately equal to 9.7 psia.
SEAT
PROCESS TEMP. (
o
F)
SET PRESSURE (3)
MATERIAL
Min.
(1)
Max.
Min.
Max.
Buna-N
-30 275 1 psi vac 14.6 psi vac
Viton
-30 400 1 psi vac 14.6 psi vac
EPR
-65 325 1 psi vac 14.6 psi vac
Kalrez
0 500 1 psi vac 14.6 psi vac
Neoprene
(2)
-20 200 0.36 psi vac 5 psi vac

INSTALLATION, OPERATION, &
MAINTENANCE MANUAL
TITLE: F70VP Series Rev. B
Vacuu Relief Valve Page 6 of 20
2.3 INSTALLATION
Prior to installation, check that the vacuum set pressure on the nameplate is as specified, and meets
system requirements. The F70VP Series vacuum relief valve should be installed in the upright position
as shown below, in accordance with accepted piping practices.
If a block valve is used below the relief valve, it should be opened before operating the system. This
block valve should be locked open during normal system operation.
2.4 STARTUP
Foreign particles or dirt can damage the valve and make it inoperative. Prior to installation, clean out the
piping thoroughly. A screen may be fastened to the open side flange on the main valve to prevent the
introduction of debris. If the valve is not installed immediately, inlet and outlet connections should be
protected and covered.
As soon as the valve is installed, the system may be brought to its operating pressure. Verify that the
valve seat is leak-tight, in accordance with Section 6.0.
The valve is now ready for service. Inspection and maintenance should be performed on a regular basis,
typically once a year, depending on the service conditions.

INSTALLATION, OPERATION, &
MAINTENANCE MANUAL
TITLE: F70VP Series Rev. B
Vacuu Relief Valve Page 7 of 20
3.0 MAIN VALVE MAINTENANCE
3.1 DISASSEMBLY OF THE F70VP SERIES MAIN VALVE
(See parts lists and illustrations on Pages 7 - 9)
CAUTION: It is extremely dangerous to attempt to disassemble any valve while it remains in
service connected to a pressure or vacuum source.
1) Remove the valve from service, or safely isolate the system before disassembling the valve and
performing maintenance.
2) If necessary, remove the pilot valve and interconnecting tubing. See Section 4.0 for pilot valve
maintenance.
3) Remove the cap bolts and lockwashers (Items 8, 9 – Pg. 8) and any lifting lugs (Item 11 – Pg. 8)
to remove the cap (Item 3 – Pg. 8).
4) With the cap removed, remove the top liner seal (Item 4 – Pg. 8). If the valve is a low pressure
1-1/2 x 2, 2 x 3, or 3 x 4, the rolling diaphragm (Item 13 – Pg. 9) must be carefully lifted up.
5) Carefully reach into the valve and remove the piston assembly (Item 6 – Pg. 8). Larger pistons
may have an interior threaded hole into which a cap bolt can be inserted to use for lifting. In high
pressure assemblies, do not be alarmed if the liner (Item 5 – Pg. 8) comes out with the piston
assembly. Care must be taken during this removal because any damage might result in an
eventual sealing problem when the valve is reassembled.
6) The liner may then be removed; again, care must be taken not to damage the liner. Do not
attempt to pry or force the liner out as you may score the surface and cause a sealing problem.
Note that on valves 4” x 6” and larger, there is a second liner O-ring seal in the main valve
counterbore where the liner is supported.
7) To remove the piston seat (Item 3 – Pg. 9), remove the retainer bolt/screw (Item 1 – Pg. 9), for
the high pressure version, and retainer (Item 2 – Pg. 9). The low pressure retainer is threaded
and needs to be unscrewed.
8) If the low pressure seat insert (Item 13 – Pg. 8) is damaged, unscrew it and remove the
accompanying seal (Item 14 – Pg. 8) from the main valve body.
9) As required, install new main valve softgoods per the instructions in Section 3.2. Replacement
soft goods are listed in Section 8.0 of this manual.
MAIN VALVE PARTS LIST
(Refer to illustrations -- Pg. 8)
Item No.
Description
2 Body
3 Cap
4 Liner seal(s)
5 Liner
6 Piston assembly
7 Pickup tube
8, 9 Cap bolts and lockwashers
10 Pilot mounting bracket (1-1/2x2 – 3x4, and all LP)
11 Lifting lug
12 Plug
13, 14 Seat insert and seal (LP only)
15 Seal and lock nut (not used on newer 3/8 NPT pickup tube
connection)

INSTALLATION, OPERATION, &
MAINTENANCE MANUAL
TITLE: F70VP Series Rev. B
Vacuu Relief Valve Page 8 of 20
Assembly Illustration: 1-1/2” x 2” through 3” x 4”
HIGH PRESSURE LOW PRESSURE
MAIN VALVE SUBASSEMBLY MAIN VALVE SUBASSEMBLY
( 5 psi vac. – 14.6 psi vac. ( 0.36 psi vac. – 5 psi vac.
Assembly Illustration: 1” x 2” and 4” x 6” through 12” x 16”

INSTALLATION, OPERATION, &
MAINTENANCE MANUAL
TITLE: F70VP Series Rev. B
Vacuu Relief Valve Page 9 of 20
Piston Assembly Illustrations
F70VP HIGH PRESSURE F70VP LOW PRESSURE
PISTON ASSEMBLY, 1x2 – 3x4 PISTON ASSEMBLY
(On 4x6 and up: Qty. of 2 Item 5, no Item 5a; 4 x 6 & 6 x 8
Item 5a optional on smaller sizes)
F70VP LOW PRESSURE
PISTON ASSEMBLY
1-1/2 x 2, 2 x 3, & 3 x 4
PISTON ASSEMBLY PARTS LIST
Item No.
Description
1 Retainer screw
2 Seat retainer
3 Seat
4 Piston body
5 Wear ring (“Slydring”)
5a Backup ring
6 Piston seal
7 Heli-Coil
8 Skirt
9 Bushing
10 Stem
11 Diaphragm guide
12 Diaphragm retainer
13 Rolling diaphragm
14 Set screw
15 Guide ring

INSTALLATION, OPERATION, &
MAINTENANCE MANUAL
TITLE: F70VP Series Rev. B
Vacuu Relief Valve Page 10 of 20
3.2 REASSEMBLY OF THE F70VP SERIES MAIN VALVE
1) Reassembly of these valves is basically the reverse of disassembly. Care must be taken in the
handling of all items, particularly sealing surfaces and softgoods. All parts should be clean and
free of any debris or contaminants.
2) Reinstall the liner (Item 5 – Pg. 8) and liner seals (Item 4 – Pg. 8) into the body. Do not nick or
excessively stretch the liner seal O-rings. The bottom O-ring (for 4 x 6 and larger) may be
carefully set in its sealing area in the body before the liner is inserted, or it may be fitted onto the
liner and, if necessary, held in place with a suitable lubricant (e.g., Molykote). The top liner seal
should be lightly pressed into place in its groove, such that it is evenly spread around the liner
circumference and will not be pinched when reinstalling the valve cap.
3) Insert the main seat (Item 3 – Pg. 9) into the bottom of the piston, using care to position the seat
completely within the piston O-ring groove. NOTE that any scratches, gouges, or particles on the
seat may result in a sealing problem. Carefully position the retainer plate (Item 2 – Pg. 9) over
the seat. For high-pressure pistons, insert the retainer bolt (Item 1 – Pg. 9) and tighten firmly
[NOTE: Female thread in piston must have locking thread insert (Item 7 – Pg. 9)]. For low
pressure pistons, the retainer is threaded and needs to be tightened.
4) Install the piston seal and backup ring (if provided), or rolling diaphragm, as applicable. A light
lubricant (e.g., Molykote or Lubriplate # 105) may be applied to the O-ring.
5) Fit the wear rings (Item 5 – Page 9) in their proper groove around the piston assembly. While
holding the wear rings (especially the free ends) in place, lower the piston assembly into the liner.
The piston should move freely up and down, with very little resistance from the seal and wear
rings, and should fall through the liner on its own weight. It is critically important that this
installation result in even seating of the soft seat onto the nozzle lip in the valve body.
6) After checking placement of the top liner seal [see Step (2)] and low pressure rolling diaphragm, if
applicable, the valve cap can be positioned on top of the body.
7) The cap bolts, with washers, can then be reinserted. Apply anti-seize compound to bolt threads.
The following torque values are recommended:
Main Valve Size Cap Bolt Size Torque (ft-lbs)
1-1/2x2 1/4-20UNC 8 - 10
1x2, 2x3, 3x4, 4x6 1/2-13UNC 50
6x8, 8x10, 10x12, 12x16 3/4-10UNC 120
8) If removed previously, reinstall the pilot valve and tubing. The pilot mounting bolts should be
treated with Loctite or Vibra-tite, if available, and firmly tightened.
9) The main valve is now completely assembled, and should be tested per Section 6.0 before being
returned to service.

INSTALLATION, OPERATION, &
MAINTENANCE MANUAL
TITLE: F70VP Series Rev. B
Vacuu Relief Valve Page 11 of 20
4.0 PILOT VALVE MAINTENANCE
4.1 F100 PILOT VALVE (HIGH PRESSURE: 2 – 14.6 psi vac) (See Illustration on Page 12)
A. Disassembly
CAUTION: It is extremely dangerous to attempt to disassemble any valve while it remains in
service connected to a pressure or vacuum source.
1) Remove the pilot valve from the main valve, or safely block the incoming pressure before
disassembling the valve and performing maintenance.
2) Unscrew the pressure adjustment (PA) screw cap from the PA screw. Loosen the lock nut.
3) Loosen but do not remove the PA screw from the bonnet.
4) Using a 7/16” wrench, remove the bolts, nuts, and lockwashers that hold the valve body and
bonnet in place. Separate the bonnet from the body. Remove spring and two spring washers.
5) With a 9/16” wrench on the diaphragm lock nut and screwdriver in the top of the spindle, loosen
the lock nut from the spindle.
6) Remove inner/outer spacer(s) from the top of the valve body. Remove the diaphragm from the
spindle by unscrewing it counterclockwise.
7) Turn the pilot valve body over and, using a 7/8” wrench, remove the nozzle and spindle. Unscrew
retainer screw from spindle. Remove the retainer and seat.
8) Replacement soft goods are listed in Section 8.0 of this manual.
B. Assembly
NOTE: Exercise care in handling softgoods, nozzles, and other sealing surfaces.
1) Confirm vacuum setting and associated parts required per Section 5.0.
2) Place the valve body in a vise.
3) Apply Loctite to retainer screw and use it to attach seat and retainer to spindle. Insert spindle into
the body. Lightly lubricate nozzle O-ring with Dow Corning 33 or equal, fit over nozzle, and then
tighten nozzle into body with nozzle seal. Check that there is vertical movement of spindle
assembly (0.030" minimum). With spindle in down position, check that the spindle shoulder is
within +0.010” / -0.005” of top surface of body.
4) Carefully assemble the diaphragm to the top of the spindle by slowly turning the diaphragm
clockwise on the spindle threads until it bottoms on the shoulder. Make sure that there are no
tears or rips in the diaphragm material.
5) Assemble the spacer(s) and lock nut to the spindle. With a wrench on the nut, and a screwdriver
in the top of the spindle, tighten the parts together. Apply a small drop of Loctite to the nut
threads. Make sure that the spacer is centered to the extent possible.
6) Assemble the spring and spring washers atop the spindle.
7) Assemble the bonnet over the spring / washers onto the top of the diaphragm / body. NOTE:
The gasket (shown in drawing) is only needed with the Teflon/FEP diaphragm and is installed
above the diaphragm; use of the gasket with a Buna-N or Viton diaphragm may result in leakage.
8) Insert bolts through the four holes in bonnet and body, and fasten washers and nuts.
9) Tighten the bolts to a torque of 5 - 6 ft-lbs.
10) Insert the PA screw into the top of the bonnet and install the lock nut and seal.
11) Attach PA screw cap to top of PA screw, but do not tighten.
12) Attach the bug screen to the bonnet, if necessary, so that it is facing downwards.
13) The pilot valve is now completely assembled and ready to be set per Section 5.0.

INSTALLATION, OPERATION, &
MAINTENANCE MANUAL
TITLE: F70VP Series Rev. B
Vacuu Relief Valve Page 12 of 20
Assembly Illustration: F100 Pilot Valve (High Pressure)

INSTALLATION, OPERATION, &
MAINTENANCE MANUAL
TITLE: F70VP Series Rev. B
Vacuu Relief Valve Page 13 of 20
4.2 F100 PILOT VALVE (LOW PRESSURE: 0.36 to 5 psi vac) (See Illustration on Page 14)
A. Disassembly
CAUTION: It is extremely dangerous to attempt to disassemble any valve while it remains in
service connected to a pressure or vacuum source.
1) Remove the pilot valve from the main valve, or safely block the incoming pressure before
disassembling the valve and performing maintenance.
2) Unscrew the pressure adjustment (PA) screw cap from the PA screw. Loosen the lock nut.
3) Loosen but do not remove the PA screw from the bonnet.
4) Using a 7/16” wrench, remove the bolting that holds the two halves of the diaphragm housing in
place. With the housing separated, the spring, two spring washers, diaphragm, support plate,
and top of the spindle will be accessible.
5) With a 9/16” wrench on the diaphragm lock nut and screwdriver in the top of the spindle, loosen
the lock nut and remove it from the spindle.
6) Remove support plate from the top of the spindle. Remove the diaphragm from the spindle by
unscrewing it counterclockwise.
7) Turn the pilot valve body over and, using a 7/8” wrench, remove the nozzle and spindle. Unscrew
the retainer screw from the spindle. Remove the retainer and seat.
8) Replacement soft goods are listed in Section 8.0 of this manual.
B. Assembly
NOTE: Exercise care in handling softgoods, nozzles, and other sealing surfaces.
1) Confirm pressure setting and associated parts required per Section 5.0.
2) Place the valve body in a vise.
3) Apply Loctite to retainer screw and use it to attach seat and retainer to spindle. Insert spindle into
the body. Lightly lubricate nozzle O-ring with Dow Corning 33 or equal, fit over nozzle, and then
tighten nozzle into body with nozzle seal. Check that there is vertical movement of the spindle
assembly (0.030" minimum).
4) Carefully assemble the diaphragm to the top of the spindle by slowly turning the diaphragm
clockwise on the spindle threads until it bottoms on the shoulder. Make sure that there are no
tears or rips in the diaphragm material.
5) Assemble support plate and diaphragm lock nut to spindle. Apply a small amount of Loctite to nut
threads. With a wrench on the nut, and a screwdriver in top of spindle, tighten the parts together.
6) Assemble the spring and spring washers atop the spindle.
7) Assemble the bonnet and upper diaphragm housing over the spring / washers onto the top of the
diaphragm / body. For Teflon diaphragms only, use a diaphragm gasket on top of diaphragm. If
the bonnet had previously been separated from the upper diaphragm housing, reassemble those
two parts with upper housing gasket and bonnet bolt O-rings before joining the two halves of the
housing. Permatex sealant (or equal) should be applied to the bonnet bolt threads.
8) Insert bolts through the 15 sets of holes in the diaphragm housing halves, fasten washers and
nuts, and tighten to a torque of 5 - 6 ft-lbs. Be careful not to damage the diaphragm during this
procedure.
9) Insert the PA screw into the top of the bonnet and install the lock nut and seal.
10) Attach PA screw cap to top of PA screw, but do not tighten.
11) Attach the bug screen to the bonnet, if necessary, so that it is facing downwards.
12) The pilot valve is now completely assembled and ready to be set per Section 5.0.

INSTALLATION, OPERATION, &
MAINTENANCE MANUAL
TITLE: F70VP Series Rev. B
Vacuu Relief Valve Page 14 of 20
Assembly Illustration: F100 Pilot Valve (Low Pressure)

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MAINTENANCE MANUAL
TITLE: F70VP Series Rev. B
Vacuu Relief Valve Page 15 of 20
5.0 PILOT VALVE SET PRESSURE ADJUSTMENT
NOTE: When set on a test stand with atmospheric pressure in the pilot bonnet, positive set
pressures in “PSIG” are equivalent to vacuum set pressures in “PSI VAC” that will be
expected in service with vacuum-side tubing connected to the bonnet.
1) The set pressure for the F100 pilot valve is adjusted by turning the pressure adjusting (PA) screw
or changing spring. The pilot may be adjusted + 3% beyond the nameplate setting, not to
exceed service ratings listed in Section 2.2. This is a flowing, modulating pilot valve.
2) Contact FLOW SAFE for assistance with replacement springs. Once the proper parts have been
selected, the valve can be reassembled per Section 4.1 or 4.2.
3) Set pressure adjustments are made by turning the PA screw clockwise (in) to increase the set
pressure and counter-clockwise (out) to decrease the set pressure. Depending on test equipment
available, the valve may be set as described in (4) or (5) below.
4) Test procedure with pilot tested separately using a test plate assembly (available from Flow Safe)
as shown in the figure on Page 16:
a) Slowly increase inlet pressure to set point, which occurs when pilot exhaust is first detected
at the exhaust port shown in the figure. Before set point is reached, dome pressure and inlet
pressure should increase at approximately the same rate. Tighten down PA screw lock nut.
b) Continue to increase pressure, up to approximately 105% of set pressure, until the dome
gage drops. Dome pressure should drop to the value listed in the table below. These values
indicate the point at which the main valve piston is able to open (based on the area
differential between the piston top and main seat).
F70VP Dome Pressure % F70VP Dome Pressure %
Valve Size at Set Point *Valve Size at Set Point *
1 x 2 50 % 3 x 4 HP 68 %
1-1/2 x 2 LP 56 4 x 6 76
1-1/2 x 2 HP 63 6 x 8 80
2 x 3 LP 61 8 x 10 84
2 x 3 HP 63 10 x 12 78
3 x 4 LP 65 12 x 16 73
* Dome pressure as a percentage of set pressure
Example: For a high-pressure 3x4 set at 10 psi vac. (10 psig on test stand) to begin discharging
through the outlet, the overpressure must be enough for the pilot to vent off dome pressure until it
drops to approx. 6.8 psig (0.68 x 10).
c) If dome pressure drops to the specified value, slowly begin to lower inlet pressure until the
pilot closes and exhaust leakage stops. This leakage should stop at an inlet pressure greater
than or equal to 95% of the set pressure. If the leakage does not stop, discontinue the test
and disassemble the valve and check parts.
d) Repeat the test to verify repeatable performance.
5) Test procedure on full assembly with pilot mounted on main valve (assumes system vacuum will
act on bottom connection below main valve seat):
a) Connect the main valve side connection (flange or threads) to the test air source. Also route
a line from the air source to the 1/4” NPT pilot inlet on the back side of the pilot body.
b) Increase test pressure to set point. The pilot should actuate (exhaust), allowing the main
piston to crack open. As air flow is increased, the piston should modulate farther open.
c) As test pressure decreases to a few percent below set pressure, the pilot should close,
allowing the main piston dome volume to repressurize and close the piston.
d) Adjust the PA screw as necessary, and repeat the test to verify repeatable performance.

INSTALLATION, OPERATION, &
MAINTENANCE MANUAL
TITLE: F70VP Series Rev. B
Vacuu Relief Valve Page 16 of 20
6.0 FINAL ASSEMBLY TESTING
1) Assemble the pilot valve, if included, to the main valve or its mounting bracket with four 5/16”-
24UNF mounting bolts and nuts. Tighten the bolts securely. For assemblies without pilot, install
the tubing between the pickup tube connection and cap.
2) Install and tighten all tubing connections, including any backflow preventer check valves.
3) Mount the assembly to the test stand as follows:
NOTE: Valves specially configured for atmospheric inlet below the main seat are mounted
with the side flange toward the vacuum process. In this case, reverse the main
valve connections noted in (a) and (b) below.
a) If a vacuum test system is available, mount the bottom valve flange to the system. Draw a
vacuum of about 90% of the designated “PSI VAC” set pressure.
b) If using a positive-pressure test stand, connect the main valve side connection to the stand,
leaving the bottom (process) connection open to atmosphere. Pressurize the assembly to
about 90% of the “PSIG” equivalent of the designated “PSI VAC” set pressure.
4) Check for leaks at all joints, including tubing connections, cap, cap bolts, and main valve seating
area. There should be no leaks anywhere.
5) Verify that valve opens at set pressure by continuing to raise vacuum level or positive test
pressure to nameplate set pressure. Main piston should crack open at set pressure, but may not
lift substantially if there is insufficient volume in the test system.
a) If the assembly includes a pilot, set pressure may be adjusted as described in Section 5.0,
Step (5).
b) For valves with fixed set pressure (no pilot), opening pressure is dependent on the piston’s
weight and low sliding friction between the piston and liner. Ensure that any attachments to
the piston interior are present and secure.

INSTALLATION, OPERATION, &
MAINTENANCE MANUAL
TITLE: F70VP Series Rev. B
Vacuu Relief Valve Page 17 of 20
6) To check backflow preventer operation:
a) Connect the main valve process connection to test air source. Pilot inlet should be open to
atmosphere.
b) Raise test pressure to 5 – 10 psig. Backflow preventer check valves should route pressure to
the pilot bonnet and pilot inlet simultaneously, keeping the pilot closed and routing air into the
main valve dome to seat the piston. Check outlet for indications of leakage.
c) Slowly vent off pressure from test source. Disassemble and check/clean main valve and
backflow preventer check valve sealing surfaces if any leaks were detected. Reassemble
component(s) and repeat test.
7) Once testing is complete, the valve assembly is ready for installation. If applicable, flange
protectors should be installed and other protective measures taken during transport.
F70VP Assembly – Fixed Set Point

INSTALLATION, OPERATION, &
MAINTENANCE MANUAL
TITLE: F70VP Series Rev. B
Vacuu Relief Valve Page 18 of 20
7.0 TROUBLESHOOTING GUIDE
Symptom
Possible Cause
Remedy
The main valve leaks
around the cap or cap
bolts.
Cap bolt(s) loose, or insufficient /
uneven bolt torque.
Retighten the cap bolts per Section 3.2.
Sealing surface on cap is
damaged.
Repair defect or replace cap.
Upper liner seal is damaged or
contaminated.
If damaged, replace with new seal(s). If
contaminated, clean and reinstall.
Air trapped in cap bolt hole(s). Wait until leakage stops (applicable to
very recent cap reinstallation only).
The main valve leaks
through the bottom
(system) connection.
Damage to, or contamination on,
piston seat or main valve nozzle,
piston seal / sealing surface, lower
liner seal / sealing surface, or
backflow preventer check valve
seating surfaces.
Disassemble the valve, remove the
piston and liner, and examine seat(s),
seals, and sealing surfaces under
magnification. If damaged, replace with
new part(s); if contaminated, clean and
reinstall.
Dome is not loading properly
through the pilot.
Check pilot or tubing for obstructions;
clean / unplug.
The main valve does not
open.
Pilot valve not set correctly. Check set point on pilot. Ensure correct
pressure units are being used (“psi vac”
vs “psia”).
Vacuum not maintained in pilot
bonnet or main valve dome (region
between cap and top of piston).
Ensure tube fitting in bonnet is tight.
Verify that Teflon seal is installed under
pressure adjustment screw lock nut. If
no pilot, verify tubing and connections to
main valve cap are tight.
Inlet screen or tubing to pilot is
plugged.
Clean / unplug line.
Pilot internals are blocked or
damaged.
Disassemble pilot; check / clean parts.
Main valve piston is seized. Disassemble the valve and examine
surfaces for debris/damage. Clean or
replace parts as necessary.
The main valve does not
close, or opens above
vacuum set point.
Obstruction in main valve, pilot
valve, or tubing to main valve.
Clean / unplug. Remove any debris
between piston and liner. Provide
system filtration if necessary.
Pilot diaphragm is leaking. Disassemble pilot valve, remove and
inspect diaphragm. Replace
diaphragm.
Backflow preventer check valves
missing or installed backwards, or
leak.
Check for proper installation and seat-
tightness.
Piston or liner seal is leaking. Disassemble the valve, remove the
seals and examine. Clean or replace,
as necessary.

INSTALLATION, OPERATION, &
MAINTENANCE MANUAL
TITLE: F70VP Series Rev. B
Vacuu Relief Valve Page 19 of 20
8.0 SOFTGOODS KITS
Most common materials listed; contact Flow Safe for availability of other materials.
8.1 MAIN VALVE SOFTGOODS
Soft
goods Kit Part Number
Valve Size
High Pressure Piston
Assembly
Low Pressure Piston
Assembly
1 x 2
1-1/2 x 2
2 x 3
3 x 4
4 x 6
6 x 8
8 x 10
10 x 12
12 x 16
VPHP-01X02-DXY
VPHP-15X02-DXY
VPHP-02X03-DXY
VPHP-03X04-DXY
VPHP-04X06-DXY
VPHP-06X08-DXY
VPHP-08X10-DXY
VPHP-10X12-DXY
VPHP-12X16-DXY
-----
VPLP-15X02-DXY
VPLP-02X03-DXY
VPLP-03X04-DXY
VPLP-04X06-DXY
VPLP-06X08-DXY
VPLP-08X10-DXY
-----
-----
Contents (See drawings & parts lists on Pages 5, 7, 8, 9):
Qty. Qty.
Wear ring (HP, below 4x6) 1 Backup ring (below 4x6) 1*
(4x6 and up) 2 Seal, pickup tube (4x6 and up) 1**
Liner / cap seal (below 4x6) 1 Diaphragm (LP, below 4x6) 1
(4x6 and up) 2 Check valve seat 2***
Seat 1
Piston seal 1 * optional; may not be used in all constructions
** not needed for NPT-style connections
*** if backflow preventer provided
X / Y / Z =
Seat / Seal / Diaphragm Material
Code
D =
Seat Hardness
Code
B
V
E
Z
C
N
T
Buna-N
Viton
EPR / EPDM
Kalrez
Chemraz
Lo-temp nitrile
Teflon – FEP film (diaphragms only)
3
5
Extra soft: < 1 psig
Soft: < 50 psig

INSTALLATION, OPERATION, &
MAINTENANCE MANUAL
TITLE: F70VP Series Rev. B
Vacuu Relief Valve Page 20 of 20
8.2 PILOT VALVE SOFTGOODS
F100 Pilot Softgoods Kit: P/N F100V-BLP-DXYZ Low pressure, bracket-mount
F100V-BHP-DXYZ High pressure, bracket-mount
F100V-DHP-DXYZ High pressure, direct-mount
Contents (See drawings on Pages 12 & 14):
Qty. Qty.
Seat 1 Diaphragm gasket (for Teflon diaphragm only) 1
Diaphragm 1 Upper housing gasket (LP only) 1
Nozzle O-ring 1 Lower housing gasket (LP only) 1
Nozzle seal 1 PA screw seal 1
Small face seal (direct-mount only) 1 Bonnet bolt O-ring (LP only) 4
Large face seal (direct-mount only) 1