Samson 36-8 Service manual

Safety Excess Pressure Valve (SEV)
Type 36-8
Edition April 2007
Mounting and
Operating Instructions
EB 2546-2 EN
Fig. 1 · Type 36-8 Excess Pressure Valve

1 Design and principle of
operation
The excess pressure valve consists of a
spring-loaded globe valve with a balanced
plug and an actuator with an operating dia-
phragm and a safety diaphragm.
The excess pressure valve is used to maintain
the pressure upstream of the valve to an ad-
justed set point value. The valve opens when
the upstream pressure rises.
The process medium flows through the valve
between the seat (2) and the plug (3) in the di-
rection indicated by the arrow. The position
of the valve plug determines the flow rate. The
upstream pressure p1is transmitted via the
control line (12) to the operating diaphragm
(11.1) and is converted into a positioning
force which is used to move the valve plug,
opposing the force of the positioning springs
(7). The spring force is adjustable at the set
point adjuster (6).
The regulator has two diaphragms (11.1) op-
erating independently from one another.
Continued operation is possible even should
one diaphragm fail. To recognize a ruptured
diaphragm, a diaphragm rupture indicator
or optionally a pressure switch to signalize a
rupture is installed in the intermediate ring
(11.3 ).
Typetestng:
The regulator has been typetested as a safety
excess pressure valve (SEV) by the German
Technical Inspectorate (TÜV) according to
AGFW specifications.
The test mark is available on request.
2EB 2546-2 EN
Design and principle of operation
4
The regulators must be mounted, started up and serviced by fully trained
and qualified personnel only, observing the accepted industry codes and
practices. Make sure employees or third persons are not exposed to any
danger.
All safety instructions and warnings in these instructions, particularly those
concerning installation, start-up, and maintenance, must be observed.
4
Any hazards which could be caused in the excess pressure valve by the
process medium or operating pressure are to be prevented by means of
appropriate measures.
For appropriate operation, make sure that the regulator is only used in
applications where the operating pressure and temperatures do not
exceed the operating values based on the valve sizing data submitted in
the order.
4
Proper shipping and appropriate storage are assumed.

EB 2546-2 EN 3
Design and principle of operation
12
1
3
2
p
2
p
1
4
6
5
7
8
11.1
9
11.3
11.2
11
10
1 Valve body
2 Seat
3 Plug
4 Plug stem
5 Balancing bellows
6 Set point adjuster
7 Positioning springs
8 Bellows
9 Fastening nut
10 Support
11 Actuator housing
11.1 Diaphragms
11.2 Diaphragm rupture
indicator
11.3 Intermediate ring
12 Control line
Drawn turned
by 90° into the
plane of projection
Fig. 2 · Sectional drawing

2 Installation
2.1 Position of installation
Note!
Flush the pipeline thoroughly prior to installa-
tion of the regulator, ensuring that sealing
particles and other impurities carried along
by the process medium do not impair proper
operation, especially tight shut-off.
Install the excess pressure valve in horizontal
pipelines with the actuator suspended down-
wards.
On installing the valve, check that the medium
flows in the same direction as indicated by the
arrow on the valve body.
On choosing the point of installation, it is im-
portant to make sure that the regulator can
still be easily accessed after completion of the
plant.
The regulator must be installed free of stress. If
necessary, support the piping near the con-
necting flanges.
Note!
Never attach supports to the valve or actua-
tor.
2.2 Shut-off valve, pressure
gauge
Ideally hand-operated shut-off valves should
be installed both upstream and downstream
of the regulator. This allows the plant to be
shut down for cleaning and maintenance rou-
tines, or when the plant is not operated for
long periods of time.
To monitor the pressures in the plant, pressure
gauges should be installed upstream and
downstream of the regulator.
4EB 2546-2 EN
Installation
Fig. 3 · Installation example
12 451
1 Shut-off valve
2 Upstream pressure gauge
3 Strainer
4 Pressure reducing valve
5 Downstream pressure gauge

3 Operation
3.1 Start up
Open the hand-operated shut-off valve
downstream of the excess pressure valve.
Then open slowly the shut-off valve upstream
of the excess pressure valve.
3.2 Set point adjustment
The excess pressure required (upstream pres-
sure p1) is set by turning the set point adjust-
ment (6) with an open-end wrench, up to
DN 50 with flats across width SW 19 and
from DN 65 upwards with SW 22.
Turning it clockwise increases the upstream
pressure and turning it counterclockwise re-
duces it.
The pressure gauge located on the upstream
pressure side allows the adjusted set point to
be monitored.
4 Troubleshooting
Should the excess pressure (pressure gauge
located on the upstream pressure side) devi-
ate significantly from the adjusted set point
value, check first the control line (12) for any
blockages (section 4.1).
If the diaphragms are damaged, the actuator
can be disassembled and the diaphragms
(11.1) can be replaced (section 4.2).
If other causes such as a damaged seat or
plug are found, we recommend that you con-
tact our customer service center or return the
regulator to the manufacturer for repair.
Caution!
If the repair is to be performed by the plant
operator, it is important to take into account
when assembling and disassembling the reg-
ulator that the valve springs (7) for valve nom-
inal sizes DN 15 to 50 are preloaded by up to
70 mm.
To remove the springs, only use a suitable
tool, for example, SAMSON disassembly tool
9129-2747.
Additionally it is important to make sure that
no torque is transmitted to the bellows (8),
otherwise the metal bellows will be irrepara-
bly damaged.
Remove the regulator from the pipeline be-
fore performing any repair work on it!
5EB 2546-2 EN
Operation

Prior to disassembling the excess
pressure valve, shut down the plant
by slowly closing the shut-off valves.
Relieve the corresponding part of the
plant from pressure and drain it, if
necessary.
4.1 Cleaning the control line
1. Loosen the screw joints connecting the
control line to the actuator and the valve
body, and remove the control line.
2. Blow through the control line to remove
any blockages and clean it. Reattach it to
the actuator and the valve body.
4.2 Replacing the diaphragms
Note!
When the bottom diaphragm fails, the atmo-
spheric pressure in the intermediate chamber
between the diaphragms rises to the level of
the upstream pressure. A red mark becomes
visible in the mechanical rupture indicator.
For versions with an installed pressure switch,
a visual or acoustic signal is triggered.
When the rupture indicator is activated, the
bottom diaphragm must be replaced.
1. Unscrew the control line and clean.
2. Unscrew the nuts (9) on the support (10)
and remove the actuator housing (11).
3. Disassemble the actuator housing and re-
place the diaphragm(s).
To reassemble the regulator, proceed in the
reverse order. To start up, proceed as de-
scribed in section 3.1.
EB 2546-2 EN 6
Troubleshooting

Nominal size, set point range and spare parts for actuator
5 Dimensions and weights
EB 2546-2 EN 7
Dimensions and weights
Set point
range
bar
Nominal valve size DN Actuator
DN 15...25 DN 32...50 DN 65...100
Sur-
face
cm²
Diaphragm material
EPDM FKM
Act-
uator Diaph gram Act- uator Diaph gram
Required spring(s)
Order no. 0270-
Order no.
1070- 0520- 1070- 0520-
2 to 4.4 2166 2167 2166 2167 1410 2203
80 9500 0868 9508 0869
2.4 to 6.6 2166 2168 2166 2199 1410 1417
6 to 11 2200 2201 2200 2201 1416 2204
Nominal size
DN 15 20 25 32 40 50 65 80 100
Length L 130 150 160 180 200 230 290 310 350
Height H 415 470 600 615
Weight 1)
approx. kg 13 14 14.5 20 22 22.5 41.5 48.5 57.5
1) Weights for PN 16,
+10 % for spheroidal graphite iron PN 25 and cast steel PN 40
L
ØD 30
H

6 Customer inquiries
Please submit the following details: (see also
name plate)
4Type and nominal size
4Order number and model number
4Upstream and downstream pressure
4Flow rate in m³/h
4Has a strainer been installed?
4Installation drawing
SAMSON AG · MESS- UND REGELTECHNIK
Weismüllerstraße 3 · 60314 Frankfurt am Main · Germany
Phone: [phone] · Fax: [phone]
Internet: http://www.samson.de EB 2546-2 EN
S/Z 2007-04

Conversion from chromate coating to iridescent passivation
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Conversion from chromate coating to
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