Yoshitake GPK-2001 User manual

■EPDT-098a■
Model GPK-2001, GPK-2003
PRESSURE REDUCING VALVE
Installation & Operation Manual
Thank you very much for choosing the Yoshitake’s product. To ensure the correct and safe use
of the product, please read this manual before use. This manual shall be kept with care for
future references.
―――――――The following safety symbols are used in this manual. ――――――――
Warning
Caution
Contents
1. Specifications ····························································1~2
2. Dimensions and Weights ·············································2~3
3. Operation ·································································4~6
4. Nominal Size Selection Method
4.1 Specifications selection chart ····································· 7
4.2 Safety valve setting pressure chart ······························ 7
4.3 Characteristics chart················································· 8
4.4 Nominal size selection chart······································· 9
4.5 Nominal size selection calculation formula····················10
5. Installation
5.1 Precautions for installation ········································11
5.2 Installing accessories···············································11
5.3 Piping before and after the pressure reducing valve········12
5.4 Example of piping ···················································13
6. Operating Procedure
7.1 Precautions for operation··········································14
7.2 Adjustment procedures ············································14
7. Maintenance Procedure
8.1 Troubleshooting··················································· 15~16
8.2 Precautions for maintenance and inspection ·················16
8.3 Disassembly······················································· 16~17
8.4 Precautions during reassembly ··································17
8.5 Exploded drawing ················································ 18~19
Warranty Information
This symbol indicates a potentially hazardous situation that, if not
avoided, could result in death or serious injury.
This symbol indicates a hazardous situation that, if not avoided, may
result in minor or moderate injury. (“Caution” may also be used to
indicate other unsafe practices or risks of property damage.)

■EPDT-098a■
-1-
1. Specifications
[Models]
Model
Nominal pressure
Connection
Nominal size
The ratio of control pressure
to setting pressure
GPK-2001
2.0 MPa
Screwed
15 ~ 50A
1: 1
Flanged
15 ~ 100A
1.0 MPa
GPK-2003
2.0 MPa
Screwed
15 ~ 50A
1: 3.5
Flanged
15 ~ 100A
1.0 MPa
[Specifications]
Model
GPK-2001
GPK-2003
Reduced pressure
sensing method (*1)
External sensing
Connection
JIS Rc screwed, JIS 20K RF flanged, JIS 10K FF flanged
Nominal size
15 ~ 50A (Screwed), 15 ~ 100A (Flanged)
Fluid
Steam
Inlet pressure
0.1 ~ 2.0 MPa (JIS Rc, JIS 20K)
0.1 ~ 1.0 MPa (JIS 10K)
0.25 ~ 2.0 MPa (JIS Rc, JIS 20K)
0.25 ~ 1.0 MPa (JIS 10K)
Reduced pressure
0.05 ~ 0.9 MPa (JIS Rc, JIS 20K)
0.05 ~ 0.85 MPa (JIS 10K)
0.2 ~ 1.4 MPa (JIS Rc, JIS 20K)
0.2 ~ 0.85 MPa (JIS 10K)
85% or less of inlet pressure (gauge pressure)
System air pressure
Refer to Standard “Loading pressure - Set pressure” chart line.
Min. differential
pressure
0.05 MPa
Max. pressure reducing
ratio
20: 1
10: 1
Max. temperature
220 °C
Valve seat leakage
0.01% or less of rated flow
Material
Body
Ductile Cast iron
Main valve
Stainless steel
Main valve seat
Stainless steel
Pilot valve
Stainless steel
Pilot valve seat
Stainless steel
Diaphragm
Stainless steel
(*1) For reduced pressure sensing method, internal sensing method valves will be
available upon request.
Caution
(1) Please collate with attached nameplate and specification of ordered model.
* Please consult factory in case they do not match each other.

■EPDT-098a■
-2-
[Standard “Loading Pressure - Set Pressure” chart Line]
Basically, the set pressure to the loading air
pressure is as shown in the chart above. The
set pressure is slightly different depending on
the working conditions. For the actual use,
adjust loading air pressure suitable for the
necessary set pressure.
2. Dimensions and Weights
[GPK-2001]
•The structure differs for nominal sizes 50A to 100A.
(mm)
Nominal
Size
Screw (JIS Rc)
Flanged (JIS 20K RF)
d
L
H
H1
A
Weight
（kg）
L
H
H1
A
Weight
（kg）
15A
Rc 1/2
150
335
170
200
14.0
146
335
170
200
15.5
20A
Rc 3/4
150
335
170
200
14.0
146
335
170
200
16.0
25A
Rc 1
160
341
175
226
18.5
156
341
175
226
21.0
32A
Rc 1-1/4
180
371
192
226
21.5
176
371
192
226
24.0
40A
Rc 1-1/2
180
371
192
226
21.5
196
371
192
226
24.5
50A
Rc 2
230
435
216
276
33.0
222
435
216
276
36.0
65A
―――
－
－
－
―
―――
282
489
251
352
64.5
80A
―――
－
－
－
―
―――
302
512
264
352
71.5
100A
―――
－
－
－
―
―――
342
595
321
401
111.0
* Different Length (L) and Weight values apply for JIS 10K FF.
* Other standard connections are available upon request.
(Screwed)
(Flanged)

■EPDT-098a■
-3-
[GPK-2003]
•The structure differs for nominal sizes 50A to 100A.
(mm)
Nominal
Size
Screw (JIS Rc)
Flanged (JIS 20K RF)
d
L
H
H1
A
Weight
（kg）
L
H
H1
A
Weight
（kg）
15A
Rc 1/2
150
353
170
200
17.5
146
353
170
200
19.0
20A
Rc 3/4
150
353
170
200
17.5
146
353
170
200
19.5
25A
Rc 1
160
359
175
226
22.0
156
359
175
226
24.5
32A
Rc 1-1/4
180
389
192
226
25.0
176
389
192
226
27.5
40A
Rc 1-1/2
180
389
192
226
25.0
196
389
192
226
28.0
50A
Rc 2
230
453
216
276
36.5
222
453
216
276
39.5
65A
―――
－
－
－
―
―――
282
507
251
352
68.0
80A
―――
－
－
－
―
―――
302
530
264
352
75.0
100A
―――
－
－
－
―
―――
342
613
321
401
114.5
* Different Length (L) and Weight values apply for JIS 10K FF.
* Other standard connections are available upon request.
(Screwed)
(Flanged)

■EPDT-098a■
-4-
Fig.1
3. Operation
The pressure reducing valve reduces pressure by the throttling the valve. The valve is
composed of the main valve, main valve seat, a pressure adjusting air chamber, and the
main diaphragm, pilot diaphragm, and pilot valve for pressure sensing and activation.
No.
Parts name
1
Body
6
Main Valve
7
Main Valve Seat
12
Main Diaphragm
13
Main Valve Spring
15
Screen
17
Pilot Valve
18
Pilot Valve Seat
23
Pilot Diaphragm
23-2
Air pressure sensing port
33
Tee
34,35,36
Pipe A,B,C
12-1
Main diaphragm chamber
23-1
Pilot diaphragm chamber
56-1
Reduced pressure sensing
port
(1) When the pressure reducing valve is mounted correctly, the main valve [6] and pilot valve
[17] should be closed by main valve spring [13] and pilot valve spring [19] when air pressure
is no-pressure. Slowly open the gate valve and allow the high-pressure fluid to flow in. Inlet
pressure is applied to the upside of the main valve. High pressure fluid passes through
screen [15] to also apply inlet pressure to the downside of the pilot valve. (Fig. 1)

■EPDT-098a■
-5-
Fig.2
Fig.3
(2) Introducing air pressure into air chamber flexes pilot diaphragm [23] to open the pilot valve.
The fluid passing through pilot valve [17] and pilot valve seat [18] enters the main diaphragm
chamber [12-1] via pipes [34] and [36]. This fluid also flows to the reduced side of the body
[1] through the orifice of tee [33] and pipe [35] that connects to the body. (Fig. 2)
(3) When the flow rate at the pilot valve exceeds the flow rate at the orifice, operating pressure
in the main diaphragm chamber raised and overrides the pressure on the upside of the main
valve and the load of main valve spring [13] to open the main valve. The fluid then begins
to flow from the inlet side. (Fig. 3)

■EPDT-098a■
-6-
Fig.4
(4) Reduced pressure is led to the pilot diaphragm chamber [56-1] via the sensing pipe and
reduced pressure sensing port [23-1]. The pilot diaphragm receives the reduced pressure to
be balanced with the air pressure. The pilot valve travel is controlled by the air pressure and
pressure applied to the pilot diaphragm due to variations in reduced pressure. This changes
the flow rate of fluid to the main diaphragm chamber, which controls the main valve travel to
obtain appropriate reduced pressure. (Fig. 4)

■EPDT-098a■
-7-
4. Nominal Size Selection Method
4.1 Pressure reducing valve specification selection chart
Refer to the above selection chart to select the most appropriate pressure reducing valve.
Find the point of intersection of inlet pressure(P1) and reduced pressure(P2). When the point
of intersection is within range(A), reduce pressure in two stages. When within range (C),
maximum performance cannot be obtained. When reducing pressure in two stages,
maximize the distance between the valves (at least 3 m).
4.2 Safety valve setting pressure chart
This chart is for setting the safety valve (for alarms) used for steam pressure reducing
valves.
Determine the reduced pressure of pressure reducing valve. Find the intersection point (A)
with the chart curve. Next, find point (B) by proceeds horizontally from point (A) to the left
until the ‘Setting pressure of safety valve’ axis. The setting pressure of the safety valve
should be higher than the pressure of the point (B).

■EPDT-098a■
-8-
4.3 Characteristic chart
(1) Flow rate characteristics chart
● Shut-off pressure rise: 0.02 MPa or less
● Offset: 10% or less of set pressure at outlet side (Minimum value: 0.0MPa)
Using the nominal size selection chart, select the nominal size of 80 ~ 90% of the flow rate,
considering pressure loss and heat loss of the gate valve and the strainer before and after
the pressure reducing valve. To fully utilize the flow characteristics of the valve, do not select
a small pipe size, considering the effects due to pipe resistance.
(2) Pressure characteristics chart
Reduced pressure is set to 0.14 MPa when inlet pressure is 1.75 MPa. The chart indicates
a variation in reduced pressure when the inlet pressure is changed within the range of 0.2
to 2.0 MPa.

■EPDT-098a■
-9-
4.4 Nominal size selection chart (External sensing)
* Please contact us on internal sensing method.
For example, take a pressure reducing valve whose inlet pressure (P1) is 0.6 MPa, reduced
pressure (P2) 0.4 MPa, flow rate 600 kg/h. When determining the nominal size, find the
point of intersection (A) of inlet pressure 0.6 MPa and reduced pressure 0.4 MPa. Vertically
proceed from point (A) to come across the flow rate 600 kg/h, and regard this point as (B).
Point (B) is between nominal sizes 20A and 25A. Select the larger nominal size (in this
example, nominal size 25A)

■EPDT-098a■
-10-
4.5 Nominal size selection calculation formula
An appropriate nominal size can be calculated by obtaining Cv value for the operating
conditions in question, as shown below.
•Calculation formula for Cv value
● Rated Cv value table (External sensing)
Nominal size
15A
20A
25A
32A
40A
50A
65A
80A
100A
Cv value
5.0
7.2
10.9
14.3
18.8
32
54
70
108
* Please contact us on Cv value of internal sensing method.
[Example]
The flow rate of the pressure reducing valve is calculated under the following conditions:
Nominal size 15A, saturated steam, Inlet pressure of 0.6 MPa = 0.7 [MPa A], Reduced
pressure of 0.4 MPa = 0.5 [MPa A], you can find that Cv value of 15A is 5.0 from the chart.
The following formula is established.
* Use a safety factor of 80 to 90% for nominal size selection in view of friction losses in
piping.
W: Max. steam flow rate [kg/h]
P1: Inlet pressure [MPa･A]
P2: Reduced pressure [MPa･A]
ΔP: P1 - P2 [MPa]
k: 1+0.0013× {superheated steam
temp.[°C] - saturated
steam temp. [ °C]}
2
P
P1 2
)PP(P138
Wk
Cv 21 + =
2
P
P1 2
1120P
Wk
Cv =
2)7.0(
)5.0( 1 2= = P P
k
PPPCv
W)(138 21 + =
1
)5.07.0(2.00.5138 +
=
hkg/338=

■EPDT-098a■
-11-
5. Installation
5.1 Precautions for installation
Warning
(1) Since the product is heavy, securely support it using lifting devices or the like when
installing. See the product weight specified in “2. Dimensions and Weights”.
* Failure to follow this notice may cause falling accident of the product, resulting in bodily
injury.
Caution
(1) Do not disassemble the valve unreasonably.
* Disassembling the valve at your discretion may affect the original performance.
(2) Before installing the product, remove foreign substances and scale from the piping.
* Failure to follow this notice may prevent the product from achieving its intended
performance due to the ingress of foreign substances and scale into the product.
(3) Install the valve so that the arrow on the valve body coincides with the direction of the fluid
flow.
* Failure to do so may prevent the valve from functioning.
(4) Install the valve perpendicularly to horizontal lines with the diaphragm chamber located at
the top.
* Failure to do so may prevent the valve from functioning.
(5) Do not connect the sensing pipe close to valves and elbows. Choose the position with the
least vibration. (Recommended straight length: 10 times the line pipe diameter)
* Failure to do so may cause inconsistent reduced pressure, which hampers correct
pressure control.
(6) Do not apply excessive load, torque or vibration to the valve.
* Doing so may result in malfunction or drastically shortened service life.
5.2 Installing accessories
Warning
(1) When installing the pressure reducing valve, be sure to connect the provided sensing pipe
and joint.
* Unless the sensing pipe is connected, the valve will not operate. Further, steam may blow
off, resulting burns.
[Sensing pipe connection method]
Connect the provided sensing pipe (φ8-2m)
and joint (φ8-R1/4) as shown in the
illustration on the left.
1. Wind sealing tapes around the joint and
insert the joint into the pressure sensing
side.
2. Fully insert the sensing pipe into the
valve and the pressure sensing side joint.
Tighten the cap nut until it can no longer
be rotated manually, and then turn the
cap nut about one and quarter times with
a tool. Note that the sensing pipe must be
connected so that the valve side is higher
than the pressure sensing side.

■EPDT-098a■
-12-
5.3 Piping before and after the pressure reducing valve
Warning
(1) When installing a safety valve for equipment protection at the outlet side of the product,
connect a blow-off pipe to the outlet side of the safety valve, and lead it to a place where
there is no risk of physical damage even if fluid blows out.
* Failure to follow this notice may result in injury and scalds in case of fluid blow out.
Caution
(1) Install a strainer (80 mesh) at the pressure reducing valve inlet side. Also, match the
nominal diameter of the strainer to the diameter of the piping on the inlet side of the
pressure reducing valve.
* Failure to do so may hamper correct pressure control, which affects the original
performance.
(2) Install a safety valve for equipment protection at the outlet side of the product.
* Failure to follow this notice may prevent the product from achieving its intended
performance due to the ingress of foreign substances and scale into the product.
(3) Install a pressure gauge at both the inlet and outlet sides of the valve.
* Failure to do so may hamper correct pressure adjustment.
(4) Install a steam trap to the inlet sides of the valve to prevent drainage problems.
* Failure to do so may result in drainage problem, affecting the original performance.
(5) When installing quick open and close valves, such as a solenoid valve, install it at inlet
side as much as possible, and secure at least 3 m from the valve.
* Failure to do so may result in malfunction or drastically shortened service life.
(6) When pressure reducing in two stages, secure at least 3 m between the valves.
* Failure to do so may result in malfunction, affecting the original performance.
(7) When the pressure reducing ratio is large, install a reducer to keep the flow velocity in the
pipe below 30 m/s or less.
* An excessively high flow velocity may cause erosion, resulting in drastically shortened
service.
(8) Install a bypass pipe around the pressure reducing valve. (Refer to 5.4 Piping example)
* Without a bypass pipe, it would be necessary to stop operation during maintenance and
inspection.
(9) Space is required above and below the center of the piping and on the conduit side for
overhaul inspection, so secure the space shown in Fig. 5 when piping.
(mm)
Nominal
size
A
B
C
GPK-2001
GPK-2003
15A
240
260
340
180
20A
25A
350
200
32A
250
270
380
40A
50A
290
310
430
220
65A
310
330
370
260
80A
320
340
390
100A
350
370
470
280
Fig.5

■EPDT-098a■
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5.4 Piping example
The remote pressure reducing valve can set several levels of pressure with a single pressure
reducing valve depending on how the pneumatic circuit for operation is constructed, and
automatic control is possible with a solenoid valve.
[Note]
The needle valve of the standard unit prevents pressure fluctuations due to volumetric expansion
of air heated by steam above the remote pressure reducing valve and the effects of volumetric
changes in the operating air pressure chamber. If the operating air pressure circuit is long, the
operating pressure - set pressure basic diagram will deviate slightly. In such cases, change the
operating pressure to achieve the required set pressure.
[Standard operating circuit]
The standard unit's air pressure reducing valve
inputs air pressure to the remote pressure reducing
valve to input the desired pressure. Use the manual
three-way switching valve to turn the air pressure
ON/OFF. Also, by using a three-way solenoid valve
as shown in Fig. 7, automatic ON-OFF control is
possible.
[Combination operation circuit]
Two sets of units are used, each of which
is pre-adjusted to an arbitrary air
pressure, and the pressure
corresponding to each air pressure is
output from the remote pressure reducing
valve by switching the solenoid valve.

■EPDT-098a■
-14-
6. Operating Procedure
6.1 Precautions for operation
Warning
(1) Do not touch the product with bare hands directly.
* Failure to follow this notice may result in scalds.
(2) Before applying steam to the product, confirm that there is no risk when steam flows into
the piping end and that piping joints are securely connected.
* Failure to follow this notice may result in scalds in case of steam blow out.
Caution
(1) Before leading fluid into the product, close the stop valves at the inlet and outlet of the
product and remove foreign substances and scale from the piping completely by using a
bypass line.
* Failure to follow this notice may prevent the product from functioning properly due to the
ingress of foreign substances and scale into the product.
(2) Adjust pressure of the bypass stop valve manually to prevent the outlet pressure from
going over the set pressure of the safety valve.
* If going over, the safety valve blows out.
(3) Before stopping operation of the product for an extended period, completely discharge fluid
from the product and close the stop valves at the inlet and outlet sides of the product.
* Failure to follow this notice may cause malfunction due to rusting inside the product and
the pipes.
6.2 Adjustment procedures
Follow the steps below, and slowly turn the adjusting screw to set pressure. Incorrect
adjustment may cause hunting, water hammer, etc., resulting in damage to the valve and other
equipment. (See “5.4 Example of piping”.)
(1) Check that all stop valves (V1 to V7) are closed.
(2) Open the stop valve (V6) for the trap installed before the pressure reducing valve.
(3) Open the stop valve (V3) and adjust the valve travel of the by-pass line stop valve (V5).
Taking enough time not to blow the safety valve, blow off the fluid to remove foreign
matter. After blowing, close the by-pass line glove valve.
(4) Set the operating air pressure to no pressure.
(5) Open the sensing pipe stop valve (V4).
(6) Open the stop valve (V2) at the outlet side of the pressure reducing valve. Adjust the
travel of the stop valve (V3) so that a little fluid flow.
(7) Confirm that the condensation is discharged from the inside of the pressure reducing
valve, and slowly open the stop valve (V1) on the inlet side.
(8) While watching the pressure gauge on the secondary side, increase the operating air
pressure with a standard unit, etc., and adjust to the desired pressure. Be sure to release
a small amount of operating air pressure with a needle valve. (For the needle valve of
the standard unit, open the valve opening by 1/2 to 1 turn.)
(9) Slowly open the stop valve (V3) and make fine adjustments so that the secondary
pressure is the desired pressure.
(10) When the adjustment is completed, secure the handle of the standard control unit’s
pressure reducing valve.
(11) Check for leakage. Conduct re-tightening as necessary.

■EPDT-098a■
-15-
7. Maintenance Procedure
7.1 Troubleshooting (Refer to “7.5 Exploded drawing”.)
Problem
Cause
Solution
Pressure does not
reach the desired
value.
1. Incorrect pressure is being used.
2. Insufficient operating air pressure.
3. Screen [15] is clogged.
4. Main diaphragm [11] is damaged.
5. Orifice of tee [33] is clogged.
6.Pilot valve [17] and pilot valve seat
[18] are clogged with foreign
matter, scales, etc.
7. Sensing pipe is clogged.
8. Nominal size is too small for the
specifications.
9. Pressure is not adjusted correctly.
10. Wrong installation with tee [33]
11. Strainer installed before pressure
reducing valve is clogged.
12. Pressure gauge is faulty.
1. Correct the pressure.
2. Increase the operating air
pressure to the desired set
pressure.
3. Disassemble and clean the
screen.
4. Replace the main diaphragm.
5. Remove the tee and clean it.
6. Disassemble pilot valve assembly,
and clean it.
7. Disassemble and clean it.
8. Change the nominal size
appropriately.
9. Observe the adjustment
procedures and readjust pressure.
10. Install the tee whose slit should
be faced upward.
11. Disassemble and clean it.
12. Replace it.
Reduced pressure
raises above than
the specified value.
1. Operating air pressure too high.
2. The relief of the operating air
pressure is small.
3. Foreign matter exists between
main valve [11] and main valve
seat [12], or scratches exist.
4. Foreign matter exists between
pilot valve and pilot valve seat, or
scratches exist.
5. Orifice of tee [33] is clogged.
6. Reduced pressure is not adjusted
correctly.
7. Foreign substances stuck
between the spindle [8] and the
guide [9].
8. Trap is not provided for dead-end
line.
9. By-pass valve is leaking.
1. Decrease the operating air
pressure.
2. Release a little of the operating
air pressure with a needle valve,
etc. (Refer to “5.4 Piping
example”.)
3 Disassemble and remove the
foreign matter. When any
scratches are identified, lap the
main valve and main valve seat.
Change the parts if scratches still
exist after lapping.
4. Disassemble the pilot valve
assembly, and clean or replace it.
5. Remove the tee and clean it.
6. Observe the adjustment steps
and readjust pressure.
7. Disassemble the product and
remove the foreign substances.
8. Install a trap.
9. Repair or replace it.
Abnormal noise is
heard.
1. Orifice of tee [33] is clogged.
2. Nominal size is too large for the
specifications.
3. Pressure reducing ratio is too
large.
4. Drainage problem is caused.
5. A quick operating valve installed
near the product.
6. Outlet pipe diameter is too small.
7. No or too much operating air
pressure relief.
1. Remove the tee and clean it.
2.Change the nominal size
appropriately.
3. Reduce pressure in two stages.
4. Install a trap.
5. Place the quick operating valve
more than 3 meters away from the
product.
6. Select a pipe size that will
produce a flow velocity of 30m/s
or less.
7. Set correctly.

■EPDT-098a■
-16-
● Foreign matter and scales in a pipe may cause most of problems of pressure reducing
valve. Be careful sufficiently to foreign matter in a pipe.
● Phenomenon alike valve trouble may happen by fault of pressure gauge, fluid leakage
from by-pass valve, forgetting to close the by-pass valve, clogging strainer, and etc.
First, check the said before above troubleshooting.
● Consult factory when cannot make a judgement whether parts need replacement or not.
7.2 Precautions for maintenance and inspection
Warning
(1) Completely discharge internal pressure from the valves, lines, and equipment, and cool
the valve down to a level where you can touch it with bare hands before disassembly and
inspection.
* Failure to do so may result in injury or burns due to residual pressure or spillage around
the valve.
Caution
(1) Pressure reducing valve shall be disassembled and inspected by qualified person or
manufacture.
* Request the treatment to specialized dealer or manufacture in case of any problems.
(2) While disassembly, drain flow out from the valve, so catch it by container. And release steam
completely before disassembling.
* In case of no container for drain, it makes dirty surrounding the valve.
(3) Close the stop valves before and after the pressure reducing valve, and remove all foreign
matter and scales via the by-pass line before operation.
* Failure to do so may prevent the valve from functioning correctly.
(4) Remove condensate completely from the line, and close the stop valves before and after the
valve when not using it for long periods of times.
* Rust generated in the valves and lines may cause malfunction.
(5) In case of no operation for a long period of time, perform operating exam before start operation
again.
* Request the treatment to specialized dealer or manufacture in case of any problems.
7.3 Disassembly
Be sure that the stop valves at inlet and outlet side of pressure reducing valve is closed and
all internal pressure and condensate have discharged before disassembling the valve.
(1) Pilot valve
1. Set the operating air pressure to no pressure.
2. Remove bolt [60] of cover [57].
3. For GPK-2001, remove the pilot diaphragm [23], the diaphragm case [58], and pilot
diaphragm plate [59].
3. Remove pilot valve assembly using a ring spanner or socket wrench (nominal size 22).
(2) Main valve
1. Remove pipe A [34] at joint A [30] or tee [33].
2. For nominal sizes 15A to 40A, remove bolt [38] of pilot body [2]. Dismount the pilot body
from the body [1]. And remove spring plate [14], screen [15], main valve spring [13], and
main valve [6]. For nominal sizes 50A to 100A, remove bolt [44] of spacer [54] and
remove the spacer from the main body [1], main valve spring [13], and entire main valve
([6], [9], [50], and [51]) (for nominal size 50A, main valve spring, and main valve [6])

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(3) Main diaphragm
1. Remove pipe C [36] at tee [33].
2. Remove bolt [41] of bottom dia. case [5]. Dismount the bottom dia. case, main
diaphragm [12], retainer [11], and spindle [9] (adapter [52] and retainer [11] for nominal
sizes 65A to 100 A).
7.4 Precautions for disassembly
Caution
(1) Check that there is no damage and scratches on the main valve, main valve seat, pilot
valve, and pilot valve seat.
* Any scratches at sealing surface lead to increase in secondary pressure. When any
scratches are identified at main valve and seat, polish them away. And, change the parts
if scratches still exist after polishing. Also, in case any scratches are identified at pilot
valve and pilot valve seat, change into pilot valve assembly.
(2) Move the sliding section (pilot valve, piston, etc.) two to three times and confirm they move
smoothly.
* If the sliding parts do not move correctly, it may cause failure problems. (Working not
correctly).
(3) Replace gaskets with new ones when reassembling.
* If the gasket is used for a long time, it may cause steam leakage problem.
(4) Assemble in the reverse order of Disassembly. And tighten the bolts evenly.
* Assemble the valve due to the order. Failure to do so may lead to not assemble correctly.
And if the hexagon bolts are not screwed correctly, it may cause steam leakage problem.

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7.5 Exploded drawing
The parts name shown in the rectangle boxes are available as consumable supply.
* Apply lubricant agent for heat/steam resistance (recommendation: SOLVEST No.110 paste,
STT Inc.) to the bottom seal area of the pilot diaphragm and the top and bottom seal area of the
main diaphragm.

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