Cashco 8900 User Manual

INSTALLATION, OPERATION AND MAINTENANCE MANUAL (IOM)

I. DESIGN AND FUNCTION:

IOM-8900

09-10

8900 Series

Emergency Relief Vents

Pressure Only or Pressure/Vacuum

SECTION I

The 8900 Series is classifi ed as an Emergency Relief
Vent (ERV). The design allows it to be used as an
emergency pressure only vent or a pressure/vacuum
vent. This Series of Vents can be constructed as top
guided or hinged design. Depending on the pressure
requirement, vents can be assembled using a stack
of weights or springs to achieve the desired set point
pressure.

The 8900 Series can provide emergency pressure
and vacuum relief beyond that furnished by the
normal pressure/vacuum vent for atmospheric and
low pressure tanks, as well as providing a convenient
access for tank cleaning, inspection and repair.

Emergency Pressure Relief Vents provide relief from
excessive internal pressure which may be caused
by an abnormal condition, such as ruptured internal
heating coils, an external fi re or a failure of the tank
blanketing system. Some Models are also design to
provide emergency vacuum relief as a result of loss
of pressure casued by a break in the tank wall or a
nozzle being dislodged from the base of the tank or

sudden cooling of the tank.

The 8900 Series provides an effective vapor
tight seal when the tank is not under emergency
conditions. If the tank outbreathing requirements
exceed the capacity of the normal pressure relief
vent, under emergency conditions, the pallet opens
to allow escape of the vapors, preventing damage
to the tank due to excessive pressure. The intergal
vacuum vent allows high fl owing relief from the same
unit.

This vent design is rugged but light weight for easy
handling, inspection and maintenance. For Models
8910 and 8920 removal of the pallet assembly allows
unobstructed access to the inside of the tank. For
Models 8930 and 8940 use handle to raise the
weighted pallet assembly and gain access to the
inside of the tank.

Product Selection Guide

Vent Function Guiding Model

Pressure Relief

Pressure/Vacuum Relief 8920

Pressure Relief

Pressure/Vacuum Relief 8940

Top Guided

(Spring Loaded)

Hinged

8910

8930

SECTION II

II. INSTALLATION:

CAUTION

When installing any Valve Concepts venting device,
any safety regulations and procedures appropriate to
the specifi c plant site must be understood and followed
in accordance with that facilities corporate legal and
advisory policies.

CAUTION

DO NOT attempt to change pressure settings, either by
adding additional weight to the pallet assembly or by
changing the spring compression without consulting
the factory.

Handle the 8900 Series carefully to insure seat
tightness. Units could be damaged by over tightening
the studs or mounting it on a tank nozzle fl ange that
is not horizontal.

Carefully inspect the relief vent to insure that
there are no packing materials inside or around
the vent housing.

Before placing the vent on the tank nozzle, the fl ange
face on the tank and the vent should be inspected.
The standard vent is supplied with fl at face fl anges
and can mate with 150# ASME or API 650 fl anges.

The connecting fl anges must be fl at within 0.015”
(.381 mm), clean and free of scratches, corrosion
and any tool marks.

Inspect the gasket and make sure it is compatible
for the service. It is recommended to use a full
faced gasket to avoid defl ection of the body fl ange.

The vent should be installed using a wire cables
or straps connected to the lifting lugs/eyebolts (39)
located around the fl ange base. This will prevent
any damage to the hood.

Lubricate all studs and nuts with an appropriate
thread lubricant. If stainless steel fasteners are
used, select an anti-seize lubricant such as moly­disulfi de.

Align the gasket with the bolt circle of the fl ange.

Lower the vent body carefully on the nozzle fl ange;
keep the gasket between the fl anges. Install the
studs and tighten the nuts by hand.

Using an alternating star pattern, tighten all the
fasteners to one-half recommended torque - see
Table 1. Make sure that the fl anges are not distorted
and that the gasket is evenly compressed. Finish
tightening fasteners to torque values in Table 1.

Gasket Dimensions

FLANGE TYPE O.D. in. I.D. in. B.C. in Bolt Hole in. Quantity

16” - 150# 23.50” 15.25’ 21.25” 1.13” 16
20 - 150#” 27.50” 19.25” 25.00” 1.25” 20
24” - 150# 32.00” 23.25” 29.50” 1.38” 20

20” - API 650 26.00” 19.25” 23.50” .75” 16

24” - API 30.00” 23.25” 27.50” .75” 20

TABLE 1

Flange

Type

150# ASME

API # 650

Size

16” 16 1.000 52 104
20” 20 1.125 63 110
24” 20 1.250 86 148

20” 20 0.625 35 53
24” 20 0.625 43 61

Qty

Holes

Bolt

(in)

(UNC)

Raised Face Flat Face

2

Torque (ft-lbs)

IOM-8900 Series

III. MAINTENANCE:

SECTION III

The 8900 Series vents do not require any sort of
routine lubrication or adjustments, but should be
checked as part of a routine plant maintenance
program to confi rm that the vents are operating
properly. The ERV is a protection device and as
such will not normally cycle when in service.

In order to inspect the pallets and pallet diaphragms
for damage the vent must be removed from the tank
nozzle. Follow all safety guidelines your company
has to decommission a vent for inspection. Cashco/
Valve Concepts does not recommend that a vent be
removed from a tank in service due to the potental
of hazardous tank vapors or fl ammable tank vapors.

SECTION IV

IV. DISASSEMBLY of the 8910 and 8920 Guided - Spring Loaded Relief Vents:

See page 8 for a listing of parts. For Model 8910 (Figure 1) disregard item numbers 5 - 25, 28, 36, 40 - 60, 62

- 74 and 76. These parts are for vacuum service option for the Model 8920 and do not pertain to the pressure
only function of the 8910.

DISASSEMBLY FOR INSPECTION

To remove the vent from the tank nozzle, loosen
and remove the fl ange bolts and nuts from the tank
nozzle and fl ange seat (1). Attach lifting cables or
straps to the lifting lugs/eyebolts (39). Be sure to
utilize all lifting lugs in order to keep the unit stable
during lifting and transportion.

SPRING UNDER COMPRESSION. Relieve spring
com pres sion per following steps. Failure to do
so may result in fl ying parts that could cause
personal injury.

B. Removal of Vacuum Spring - 8920 Only:

WARNING

WARNING

SPRINGS UNDER COMPRESSION. Relieve spring
com pres sion per following steps. Failure to do so
may result in fl ying parts that could cause personal
injury.

A. Removal of Pressure Springs:

1. Place the vent fl ange (1) on a fl at work
surface. Measure the length of each compressed
spring (33) from the top surface of the pressure
pallet (3) to the top edge of the upper spring button
(34). Place a tag on each spring (33) and record

the height measurement for each. These values
will be required at re-assembly to reset the vent
spring pressure prior to installation.

2. Loosen and remove one “top” nut (35) from
each of the adjusting screws (31). Rotate remaining
nut (35) CCW evenly in 1/2” (13 mm) increments
to prevent unequal loads on the pallet/diaphragm
assembly. Continue this process until all nuts (35)
are removed.

3. Lift up to remove upper spring buttons (34)
(hole w/small I.D.) and springs (33).

1. Remove cap screws (28) from the weather
hood (11) and lift off upper spring canister (15).
Measure the length of the pallet stem (21), top edge
of stem to the top surface of the upper spring button
(14). Record this value. It will be required during re­assembly to reset the vacuum range spring pressure
prior to installation.

Length of pallet stem ________

NOTE: DO NOT allow vacuum pallet assembly
(18) to fall as disassembly continues.

2. Rotate each nut (25) CCW one at a time to
remove and to release the compression of the spring
(16). NOTE: May need to grasp a section of the

threaded stem (21) with soft-jawed pliers to prevent
rotation of the pallet assembly (18). Maintain grip
on stem (21) while carefully lowering vacuum pallet
assembly (18) to rest on work surface below.
Lift up to remove upper vacuum spring button (14)

and spring (16).

NOTE: If vent was not supplied with a fl ame screen
(5) remove lower spring button (14) and lower spring
canister (13). If vent included a fl ame screen, before
removing button (14) and canister (13), draw match
“marks” between fl ange face of the lower spring
canister (13) and weather hood (11).

IOM-8900 Series

3

C. Removal of Pressure Pallet Assembly:

1. Rotate nut (35) CCW three revolutions
on each adjusting screw (31) to loosen connection
between adjusting screw and pallet guide (30).
Grasp adjusting screws (31) with hand and rotate
each one CCW to remove adjusting screws and
travel stops (37).

2. Remove lower spring buttons (32) (hole w/
large I.D.). NOTE: Not necessary to remove pallet

guides (30) or guide pin (75). (Factory installed with
Loctite - torqued to 15 ft-lbs.)

3. Carefully lift the pallet assembly (3) up off
the fl ange seat (1), so not to damage the seating
surface. Inspect the seat surface for any damage
including but not limited to nicks and corrosion. If
damage is found, the seat should be relapped
or remachined to smooth fi nish. If remachining
is required, contact Cashco/Valve Concepts for
assistance.

D. Inspection of Diaphragms:

1. Position the pressure pallet assembly (3) on
a work bench with the diaphragm (2) side face up.

3. According to stack orientation of the
diaphragms E.1 previous, lay new diaphragms (2) in
the pallet (3) groove. Align holes in diaphragm (2)
bolt circle over studs (29) in the pressure pallet (3).

4. Position diaphragm retainer ring (4) over
studs (29) resting fl at against the diaphragms (2).
Install 1 lock washer (26) and 1 nut (27) to each stud
(29), tighten to 5 ft. lbs. NOTE: Do not allow studs

(29) to rotate and protrude out the backside of the
pallet (3), end point of studs should be fl ush.

NOTE: For Model 8910 Vents proceed to IV. H.

For Vacuum Pallet:

1. Place threaded end of pallet stem ( 21) in a
soft-jaw vise with pallet (18) face up.

2. Remove the cotter pin (56), nut (24), lock
washer (23), and the fl at washer (22).

3. Remove vacuum pallet (18) and diaphragm
(19). Clean pallet (18), especially the pallet groove
and inspect for nicks or sctatches. NOTE: Vacuum

pressure set point will dictate the quantity and stack
orientation of diaphragms. Record diaphragm’s

stack orientation for re-assembly.

2. Inspect the diaphragms (2,19) on both
pallet assemblies (if applicable) for any signs of
damage. Damages may include but are not limited
to tears, crinkles/creases, and holes. If it is deemed
that the diaphragm(s) need to be replaced, proceed
with following steps to replace. If they are deemed
to be in good condition, inspect the vacuum seat
ring (8) for similar damages as for the fl ange seat
(1) seating surface. These include but are not
limited to nicks and corrosion. If damage is found,
the seat surface may be relapped. If relapping the
seating surface does not create a suitable seating
surface, a new seat ring is required. Contact your
local representative for assistance. Provide Serial
Number, Product Code & Set Point Pressure(s) to
place an order for parts.

E. Diaphragm Replacment:

For Pressure Pallet:

1. Remove hex nuts (27), lock washers (26),
and diaphragm retainer ring (4) from the pallet.

NOTE: Pressure set point will dictate the quantity
and stack orientation of diaphragms. Record

diaphragm’s stack orientation for re-assembly.

4. Install new diaphragm(s) (19) over short
threaded end of stem (21) onto retainer plate (20).
Apply a light coat of TFE paste on the top surface
of the last diaphragm (19) around the edge of the
center hole.

5. Place vacuum pallet (18) with the machined
groove facing down on the diaphragm (19). Apply a
light coat of TFE paste to short threaded end of stem
(21).

6. Install fl at washer (22), lock washer (23)
and nut (24) onto the protruding threads of the stem
(21). Use a torque wrench to tighten nut to 15 ft-lbs.

7. Insert cotter pin (56) thru small hole in the
stem (21) and wrap prongs around stem.

F. Vacuum Seat Ring Replacement:

- For ERV without Flame Screen:

NOTE: Installation of the pressure pallet diaphragms
should be completed prior to installation of the
vacuum seat ring.

2. Remove diaphragm (2). Clean the pressure
pallet (3), especially the pallet groove, and inspect
for nicks or scratches.

4

1. Re-Orient the pressure pallet assembly (3)
with vacuum seat ring (8) face down - use 4” x 4”
blocks as support. DO NOT ALLOW DIAPHRAGM

(2) OR RETAINER RING (4) TO REST ON THE
BLOCKS.

IOM-8900 Series

2. Rotate cap screws (36) CCW to remove
weather hood (11). Remove screen (6). Around
the bolt circle of the weather collar (7) place match
“marks” to indicate the location of each weather
hood support (10).

3. Rotate each support (10) CCW and remove.
Rotate seat ring nuts (73) CCW to remove nuts,
lockwashers (74), weather collar (7) and gasket (5).

of pallet stem (21) protrude thru upper spring button
(14). With other hand, thread one jam nut (25) on to
pallet stem (21).

NOTE: Check to ensure that as the pallet assembly
(18) is lifted upwards that the vacuum seat ring (8)
is centered and aligned with vacuum pallet (18)
assembly.

WARNING

4. Re-Orient the pressure pallet assembly (3)
with the seat ring (8) face up, again resting on the
blocks. Rotate cap screw (9) CCW and remove seat
ring (8) and seat ring gasket (5).

6. Clean sealing surfaces on seat ring (8) and
both sides of pressure pallet (3).

7. Install new seat ring gasket (5). Position
seat ring (8) on gasket (5), align holes and thread
cap screws (9) into pallet using a star pattern and
tighten to 15 ft. lbs.

8. Re-Orient the pressure pallet assembly (3)
with the seat ring (8) face down, again resting on the
blocks. Position new gasket (5) and weather collar
(7) over cap screws (9).

9. Using the “marks” per 2. previous, install the
weather hood supports (10) on the weather collar
and tighten to 15 ft-lbs.. On remaining cap screws,
install lock washers (74), nuts (73) and tighten to 15
ft-lbs..

10. Reposition the screen (6) around the
weather hood supports (10). Align holes in weather
hood (11) with holes in supports (10) and install cap
screws (36), torque to 15 ft-lbs. Install lower canister
(13) into weather hood (11).

11. From underside of pressure pallet (3)
assembly slide vacuum pallet (18) assembly ­threaded end of stem (21) fi rst, up through center
hole of lower canister (13).

12. Into the open end of the canister, install
lower spring button (14) and spring (16) over stem
(21) into the lower canister (13). Make sure that
lower spring coil rests inside the retainer groove of
the lower spring button (14).

13. Place upper spring button (14) on top of
vacuum spring (16). Make sure that top spring coil
rests inside the groove of the spring button.

SPRING UNDER COMPRESSION. Exercise cau­tion to avoid accidental spring release. Vacuum
spring (16) is now under compression and the ac­cidental release of force may result in fl ying parts
that could cause personal injury.

15. Continue to rotate jam nut (25) CW until
the height from the top of the pallet stem (21) to the
top of the upper spring button (14) is equal to the
value recorded per B.1. previous.

16. Thread a second jam nut (25) on pallet
stem (21). Secure tight against fi rst jam nut (25).

17. Place upper spring canister (15) over
vacuum spring (16), align bolt holes in canister
fl anges.

18. Insert cap screws (28) into fl ange bolt
holes and tighten snug - torque to 10 ft-lbs. NOTE:

DO NOT over tighten screws. Proceed to “H”.

G. Vacuum Seat Ring Replacement:

- For ERV with Flame Screen:

NOTE: Installation of the pressure pallet diaphragms
should be completed prior to installation of the
vacuum seat ring.

1. Orient the pressure pallet assembly (3) and
vacuum seat ring (8) face up. Note alignment of
the three cap screws in bottom of the lower spring
canister (13) with respect to the location of the cap
screws (9) around the weather collar (7). Place
match “marks” on fl ame screen (40) and on weather
collar (7) to indicate correct alignment of the fl ame
screen bolt holes during re-assembly of the fl ame
screen.

2. To dis-assemble fl ame screen from lower
spring canister (13) rotate three cap screws (28)
CCW and remove. NOTE: Support lower spring

canister (13) and lower spring button (14) from
below as cap screws are removed. They may fall
out of weather hood.

14. Place one hand on the upper spring button
(14) and compress the spring (16) until the threads

IOM-8900 Series

5