Yoshitake GD-26G User manual

■ EP D T -0 8 8 ■
MODEL GD-26G, GD-27G
Pressure Reducing Valve
PRODUCT
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 reference.
The symbols used in this manual have the following meanings.
Warning
This symbol indicates a potentially hazardous situation that, if not avoided,
could result in death or serious injury.
Caution
This symbol indicates a hazardous situation that, if not avoided, may result in
minor or moderate injury or may result in only property damage.
Table of Contents
1. Specifications
1.1 Specifications ····················································· 1
1.2 Nominal size selection ······································ 2 - 3
1.3 Flow rate characteristics chart ································ 3
1.4 Pressure characteristics chart································· 3
2. Dimensions and weights ·········································4 - 5
3. Operation ································································ 6
4. Maintenance and inspection
4.1 Precaution for operation ········································ 7
4.2 Warning and caution for operation ··························· 8
4.3 Piping example ··················································· 8
4.4 Adjusting procedure ············································· 8
4.5 Troubleshooting ·················································· 9
4.6 Warning for disassembly and inspection ················· 10
4.7 Disassembly····················································· 10
5. Exploded view ···················································11 - 12
After Sales Service

1
■ EP D T-0 8 8■
1
. Specifications
Caution
(1) Please collate with attached nameplate and specification of ordered model.
* Please consult factory in case they do not match each other.
1.1 Specifications
Model GD-26G GD-27G
Nominal size 15 - 50A 25 - 100A
Applic
ation
Air, Other non
-
dangerous fluids
Inlet pressure
1.0 MPa or less
Reduced pressure
A
0.05
-
0.35 MPa
B
0.30
-
0.70 MPa
Min. differential pressure
0.05 MPa
Max. pressure reduc
tion
ratio
10
:
1
Application temperature 5 - 90 C
Material
Body
Bronze
Valve seat
Bronze
Valve d
isc
EPDM
Diaphragm EPDM
Connection JIS Rc screwed JIS 10K FF flanged
The products of the nominal size 15A to 50A incorporate a strainer (40 mesh).
Pressure gauge connection port is JIS R1/8.
Caution
(1) For medium including oil, use fluorine rubber for disc and diaphragm.
* If not, disc and diaphragm may be broken.

2
■ EP D T-0 8 8■
1.2 Nominal size selection
<For Air>
Nominal size selection chart
[Example]
When selecting the nominal size of a pressure reducing valve whose inlet pressure (P
1
), reduced
pressure (P
2
), and flow rate are 0.3 MPa, 0.2 MPa, and 200 m
3
/h (standard condition),
respectively, first find intersection point (A) of the inlet pressure (P
1
) of 0.3 MPa and the reduced
pressure (P
2
) of 0.2MPa.
Trace down vertically from the intersection point to find intersection point (B) with the flow rate of
200 m
3
/h (standard condition). Since intersection point (B) lies between nominal size 25A and
32A, select the larger one, 32A.
R
e
d
u
c
e
d
p
r
e
s
s
u
r
e
(
M
P
a
)
(B)
R
e
d
u
c
e
d
p
r
e
s
s
u
r
e
(
M
P
a
)
(A)
Nominal
Size
F
l
o
w
R
a
t
e
m
3
/
h
(
S
t
a
n
d
a
r
d
c
o
n
d
i
t
i
o
n
)
F
l
o
w
R
a
t
e
m
3
/
h
(
S
t
a
n
d
a
r
d
c
o
n
d
i
t
i
o
n
)

3
■ EP D T-0 8 8■
Nominal size selection calculation formula
[Cv value calculation formula]
Nominal size 15A 20A 25A 32A 40A 50A 65A 80A 100A
Rated Cv value 2 2.3 3.5 6 7 11 21 26 38
1.3 Flow rate characteristics chart
Offset
Pressure
range
Reduced
pressure range
Offset
A 0.05 - 0.35 MPa
0.05 MPa
or less
B 0.30 - 0.70 MPa
0.10 MPa
or less
1.4 Pressure characteristics chart
This chart shows variation in the reduced pressure when the inlet pressure of 0.60 MPa is changed
between 0.15 MPa and 1.0 MPa after the reduced pressure is set at 0.10 MPa.
Q: Max. Fluid flow rate
[m
3
/h (standard condition)]
P
1
: Inlet pressure [MPa ･ A]
P
2
: Reduced pressure [MPa ･ A]
ΔP: P
1
－ P
2
[MPa]
G: Specific gravity
(Specific gravity per air)
t: Fluid temperature [ ℃ ]
2
P
P
1
2
)PP(P
t)G273(
2940
Q
Cv
21
2
P
P
1
2
1
P2550
t)G273(Q
Cv
Reduced pressure (MPa)
Inlet pressure (MPa)
Shut-off pressure rise
(0.02 MPa or less)
Set pressure
Min. adjustable
flow rate
Offset
Reduced pressure
Rated flow
Flow rate

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■ EP D T-0 8 8■
2
.
Dimensions and
Weights
No.
Parts name No. Parts name
1 Body 9 Diaphragm
2
Spring chamber
10
Strainer
3 Valve seat 11 Strainer cap
4
Spindle
12
Diaphragm shell
5
Retaine
r
13
Spring plate
6 O-Ring 14 Adjusting screw
7
Disc cover
15
Adjusting s
pring
8 Disc
GD-26G
(mm)
Nominal
size d L H
1
H Weight
(kg)
15
A
Rc
1
/
2
1
1
5
37.5
1
59.5
1.6
20A
Rc 3/4
1
20
38.5
1
59.5
1.7
25A
Rc 1
135
41
170
2.
1
32A
Rc 1 1/4
180
57
224
4.
0
40A Rc 1 1/2 180 57 224 4.4
50A Rc 2 200 61 239.5 6.5

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■ EP D T-0 8 8■
GD-27G 25A-50A
GD-27G 65A-100A
(mm)
Nominal
size L H
1
H JIS 10K FF Flanged Weight
(kg)
d D C t n- h
25A 160 41 170 25 125 90 14 4-19 5.1
32A 200 57 224 32 135 100 16 4-19 7.5
40A 200 57 224 40 140 105 16 4-19 7.7
50A
220
61
239.5
50
155
120
16
4
-
19
10.
9
65A
220
77
329
65
175
140
18
4
-
19
20.
0
80A
230
82
345
80
185
150
18
8
-
19
22.0
100A
270
94
412
100
210
175
18
8
-
19
3
3.0

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■ EP D T-0 8 8■
3
.
Operation
The adjusting screw [14] compresses the
adjusting spring [15], pushes down on the
diaphragm [9], and opens the disc [8] that is
directly connected to it.
The fluid that entered from the primary side
flows out from the upper part of the disk [8] to
the secondary side, and at the same time, acts
directly on the diaphragm [9] as the secondary
side pressure.
When the sluice valve on the secondary side is
closed, the pressure applied to the diaphragm
[9] increases, overcomes the load of the
adjustment spring [15], and the disc [8] closes.
Gradually opening the sluice valve on the
secondary side reduces the pressure applied to
the diaphragm [9] and opens the disc [8].
The fluid flowing out to the secondary side acts
on the diaphragm [9] as the secondary side
pressure, balances with the load of the
adjustment spring [15], adjusts the valve
opening, and keeps the secondary side
pressure constant.

7
■ EP D T-0 8 8■
4
.
Maintenance and inspection
4.1 Precaution for operation
Caution
1. Do not disassemble the product unless it is necessary.
* Unnecessary disassembly prevents the product from functioning properly.
2. Before installing the product in the piping, be sure to remove foreign substances and scale from
the piping.
* Ingress of foreign substances, scale or seal agent into the product leads to valve leakage or
malfunction of the product.
3. Be sure to install a strainer at the inlet side of the product of nominal size 65A to 100A.
* Ingress of foreign substances or scale into the product leads to malfunction of the product. It is
recommended to use a strainer of 40 mesh or more.
4. Install a safety relief valve for equipment protection at the outlet side of the product.
* Failure to follow this notice may result in damage of the equipment.
5. Be sure to install pressure gauges at the inlet and outlet sides of the product.
* Failure to follow this notice hampers correct pressure adjustment.
6. If a quick operating valve such as a solenoid valve is installed, place it at a distance of at least 3
meters from the product.
* Failure to follow this notice may result in malfunction or a drastically shortened service life of the
product.
7. For two-stage pressure reduction, keep a distance of at least 3 meters between each product.
* Failure to follow this notice may prevent the product from functioning properly due to malfunction.
8. Install the product properly by checking the inlet, outlet and proper posture.
* Installing the product in wrong directions prevents the product from functioning properly.
9. Install pipes so that excessive load, torque or vibration is not applied to the product.
* Failure to make durability lower or cause malfunction.
(1) The product can be installed either horizontally or vertically.
(2) A space more than the value shown as H
2
in the table below is required for disassembly and
inspection. A space more than the value shown as H
3
in the table below is required for the
inspection of the built-in strainer (nominal size 15A to 50A).
(mm)
Nominal size
1
5A
20A
25A
32A
40A
50A
65A
80A
100A
H
2
2
40
250
250
300
300
320
450
450
550
H
3
8
0
90
90
120
120
150
--- ---
-
--

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■ EP D T-0 8 8■
4.2 Warning and caution for operation
Warning
When the product is used for hot fluid, do not touch the product with bare hands.
* The product having hot fluid may scald your skin.
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. To adjust the set pressure, turn the adjusting screw slowly.
* Failure to follow this notice may result in damage to the product and other equipment due to
hunting or other cause.
3. When the product is not used for an extended period, completely discharge fluid from the product
and pipes, and close the stop valves at the inlet and outlet sides of the product.
* Failure to follow this notice causes malfunction of the product due to rusting inside the product
and the pipes.
4.3 Piping example
4.4 Adjusting procedure
Following a wrong adjusting procedure may cause hunting, scale problems or other problem, and can
heavily damage the main parts of the valve. To avoid these problems, be sure to follow the procedure
given below.
1. Close the stop valves at the inlet and outlet sides of the reducing valve, and take adequate time to
blow out fluid by using a bypass line. In doing this, adjust the opening of the globe valve in the by-
pass pipe so as not to blow out the safety relief valve. After the end of blowing, close the globe
valve without fail.
2. Fully open the stop valve at the inlet side slowly, and open the stop valve at the outlet side so that
a little fluid can flow through.
3. Remove the domed cap nut and turn the adjusting screw [14] while watching the pressure gauge
at the outlet side.
Turn the adjusting screw to the right (clockwise) to increase the reduced pressure.
Turn the adjusting screw to the left (counterclockwise) to decrease the reduced pressure.
4. Fully open the stop valve at the outlet side slowly.
5. After the adjustment is complete, tighten the domed cap nut.
By
-
pass
Globe valve
Pressure gauge
Inlet side
Stop
valve GD-26GS
Stop
valve
Pressure
gauge Safety valve
Outlet side

9
■ EP D T-0 8 8■
4.5 Troubleshooting
Trouble
Cause
Remedy
Reduced pressure
does not reach the
desired value.
1. The working pressure is improper. 1. Correct the working pressure. (See
“
2
.1
Specifications
”
.)
2. The nominal size of the product is
too small for the flow rate for use.
2. Replace the product with the proper
nominal size.
3. Pressure adjustment is improper. 3. Readjust the pressure in
accordance
with the given procedure.
4. Strainer built in the product is
clogged.
4. Clean the strainer.
5
.
Pressure gauge is broken.
5
.
Replace pressure gauge.
Abnormal pressure
rises at the outlet
side.
1.
Foreign substances stuck between
the disc [8] and the valve seat [3],
or scratch on them.
1. Disassemble the product and
remove the foreign substances. If
scratch is observed on the valve
dis
c
or valve seat, replace
it
.
2. The O-ring [6] is damaged. 2. Replace the O-ring.
3
.
The diaphragm [9]
is damaged.
3
.
Replace the diaphragm.
4. There is a leakage from the globe
valve of the by
-
pass line.
4. Repair or replace the globe valve.
Abnormal sound
1. The nominal size of the product is
too large for the specifications of
the system.
1. Replace the product with the proper
nominal size.
2. The pressure reduction ratio is too
large or the maximum pressure
difference is exceeded.
2. Reduce pressure in two stages.
(See “2.1 Specifications”.)
3. A quick operating valve is located
near the product.
3. Keep a distance between them as
large as possible.
Most of problems with the pressure reducing valve are caused by foreign substances and scale in
the piping. Avoid the ingress of dust and dirt to the product with caution.
A phenomenon similar to valve failure could occur due to the failure of the pressure gauge,
leakage or insufficient tightening of the globe valve in the by-pass line, clogging of the strainer,
and other causes. Check the above possible causes and take a proper remedy and preventive
measures.

10
■ EP D T-0 8 8■
4.6 Warning for disassembly and inspection
Warning
1. Completely discharge the pressure inside of the product, piping and equipment before disassembly
and inspection. Disassembly and inspection must be done by experienced professional or valve
manufacturer.
* Failure to follow this notice may result in scalds, injury or contamination on the surroundings due
to the residual pressure.
4.7 Disassembly
1. Exhaust pressure in the piping completely and check if pressure is 0 MPa by pressure gauge.
2. Remove the domed cap nut, turn the adjusting screw [14] counterclockwise, and set the spring
[15] free (no load).
3. Remove the bolts of the spring chamber [2] and remove the spring chamber [2]. Then take out the
spring [15] and the spring plate [13].
4. Remove the nut, and then the diaphragm shell [12], and diaphragm [9].
5. Remove the set screws of the valve seat [3], and remove a set of the valve seat.
Nominal size 15A to 50A: Attach the diaphragm shell [12] to the spindle [4], and pull it up.
Nominal size 65A to 100A: Screw the bolt into the valve seat [3], and pull it up.

11
■ EP D T-0 8 8■
5
.
Exploded view
Nominal size 15A - 50A

12
■ EP D T-0 8 8■
Nominal size 65A-100A

2015.8
PDD-046e
Warranty Information
1. Limited warranty
This product has been manufactured using highly-advanced techniques and subjected to
strict quality control. Please be sure to use the product in accordance with instructions on
the manual and the label attached to it.
Yoshitake warrants the product to be free from any defects in material and workmanship
under normal usage for a period of one year from the date of receipt by the original user, but
no longer than 24 months from the date of shipment from Yoshitake’s factory.
2. Parts supply after product discontinuation
This product may be subject to discontinuation or change for improvement without any prior
notice. After the discontinuation of the product, Yoshitake supplies the repair parts for 5
years otherwise individually agreed.
3. This warranty does not cover the damage due to any of below:
(1) Valve seat leakage or malfunction caused by foreign substances inside piping.
(2) Improper handling or misuse.
(3) Improper supply conditions such as abnormal water pressure/quality.
(4) Water scale or freezing.
(5) Trouble with power/air supply.
(6) Any alteration made by other than Yoshitake.
(7) Use under severe conditions deviating from the design specifications
( e.g. in case of corrosion due to outdoor use).
(8) Fire, flood, earthquake, thunder and other natural disasters.
(9) Consumable parts such as O-ring, gasket, diaphragm and etc.
Yoshitake is not liable for any damage or loss caused by malfunction or defect of the product.
INTERNATIONAL DEPT.
955-5, Miyamae, Irukadeshinden, Komaki, Aichi, 485-0084, Japan
Phone: [phone] Fax: [phone]
E-mail: [e-mail]