Yoshitake GD-24GS User manual

■EPDT-175d■
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 )
Model GD-24GS
Pressure Reducing Valve
Installation & Operation Manual
Please read this manual thoroughly before using the pressure reducing valve, so that
you may do so correctly and safely
Please carefully store this manual in a handy place
－－－－－The following safety symbols are used in this manual －－－－－
Warning
Caution
Contents
1 Specifications ································································ 1
2 Dimensions and Construction
2 1 Dimensions and Weight ················································· 2~3
2 2 Construction ·································································· 4
3 Operation ··········································································· 4
4 Nominal Size Selection
4 1 Nominal Size Selection Chart ············································ 5
4 2 Flow Rate Characteristics Chart ········································ 6
4 3 Pressure Characteristics Chart ·········································· 6
5 Installation
5 1 Piping Example ······························································ 7
5 2 Warning and precaution on installation ························ 7~8
6 Operating Procedure
6 1 Warning and precaution on operation ································· 8
6 2 Adjustment Procedure ···················································· 8
7 Maintenance Procedure ························································· 9
7 1 Warning and precaution on maintenance and inspection ···· 9
7 2 Troubleshooting ···························································· 10
8 Exploded Drawing ······························································ 10
After Sales Service

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GD-24GS pressure reducing valve for water (Hereinafter so called pressure reducing valve) is an
all-purpose valve suitable for various applications, such as water supply systems of general
residential housing, high-rise buildings, industrial plants, and factory equipment It can also be used
to provide stable water pressure in high-rise apartment units, and for hilly areas where each house
requires an individual water supply system High durability is achieved through the use of a
stainless steel valve seat and a suspension type clamp in the drive mechanism
1 Specifications
Model GD-24GS
Nominal size 15～50A
Application (Fluid) Hot or cold water
Inlet pressure 0 2～1 6MPa
Reduced pressure 0 05～0 55MPa
Min differential pressure 0 05MPa
Max pressure reducing ratio 10: 1
Temperature 5～80℃ (*)
Material
Body Bronze
Valve (Disc) Urethane rubber
Valve Seat Stainless steel
Diaphragm NBR
Connection JIS Rc
*GD-24GS is a set of pressure reducing valve (GD-24), pressure gauge, and strainer (SY-24)
*The pressure gauge and strainer are included with the product, so attach them to the pressure
reducing valve when installing the piping on site
*The Screen of strainer is 60 mesh (standard mesh)
*The Pressure gauge connection size is R 1/8
*The accuracy of the pressure gauge is ±3 0%F S
*The valve can be mounted in horizontally and vertically
(*) Avoid continuous use at 70 ℃
Caution
Please collate with attached label or plate and specification of ordered model
*Please consult factory in case they do not match each other

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2 Dimensions & Construction
2 1 Dimensions & Weight
【GD-24GS】
(mm)
Nominal
size d L H H1 Weight (kg)
15A Rc 1/2 150 197 5 46 2 1
20A Rc 3/4 169 216 51 2 8
25A Rc 1 193 243 63 3 9
32A Rc 1 1/4 236 285 80 5 7
40A Rc 1 1/2 286 343 90 9 7
50A Rc 2 343 404 112 17 5
【GD-24】
(mm)
Nominal
size d L H H1 Weight (kg)
15A Rc 1/2 80 193 41 5 1 8
20A Rc 3/4 90 210 45 2 4
25A Rc 1 100 230 50 3 3
32A Rc 1 1/4 120 265 60 4 7
40A Rc 1 1/2 150 315 62 8 2
50A Rc 2 185 365 73 14 3

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【Pressure gauge】
【SY-24】
(mm)
Nominal
size d d1 L H1 Screen Weight (kg)
ds ls
15A Rc 1/2 R 1/2 80 46 18 32 0 25
20A Rc 3/4 R 3/4 90 51 20 35 0 35
25A Rc 1 R 1 105 63 25 50 0 55
32A Rc 1 1/4 R 1 1/4 130 80 32 60 1 00
40A Rc 1 1/2 R 1 1/2 150 90 40 70 1 44
50A Rc 2 R 2 175 112 50 85 2 90

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2 2 Construction
No Name of parts
1 Body (GD-24)
2 Spring Chamber
3 Cap
4 Valve (Disc)
5 Valve Seat
6 Suspension Metal
7 Diaphragm Shell
8 Diaphragm
9 Spring Plate
10 Adjusting Screw
11 Lock Nut
12 Spring Lock Washer
13 Nut
14 Adjusting Spring
15 O-ring
16 Bolt
17 Sealed Nut
18 Spring
19 Pressure Gauge
20 Body (SY-24)
21 Cap
22 Screen
23 O-ring
24 Label
25 Spring Washer
Caution
Be sure to remove the plug of the pressure gauge mounting part that was installed at the time
of shipment and replace it with the included pressure gauge
*
Corrosion resistance is not considered because the plug is for airtightness test at the time of
shipment
3 Operation
(Refer to the parts number in “2 2 Construction”)
Turning the adjusting screw (10) to compress the adjusting spring (14) and the load of adjusting
spring is introduced to the diaphragm (8) and suspension metal (6) to open the valve (4) Then,
the fluids begin to flow from the inlet side through the upper side of the valve The reduced
pressure is led to the diaphragm to be balanced with the adjusting spring load, and control the
valve travel to maintain the reduced pressure

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4 Nominal Size Selection
4 1 Nominal Size Selection Chart (For Water)
Note: *The Chart shown above is for a GD-24 valve without SY-24
*Considering such factors as noise and durability, a 2 m/s flow velocity
within the pipe is ideal
●Cv Value
Nominal size 15A 20A 25A 32A 40A 50A
Cv value 1 5 1 9 3 4 7 10
●Calculation formula for Cv value
P
GV
Cv
∆
=365.0
P1 : Inlet pressure [MPa･A] V : Rated flow rate [m3/h]
P2 : Reduced pressure [MPa･A] G : Specific gravity relative to water
ΔP : P1－P2 [MPa] Cv : Cv value of the nominal size
ΔP: Inlet/reduced pressure differential (MPa)
V: Flow rate (m
3
/h)
Nominal size

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4 2 Flow Rate Characteristics Chart
4 3 Pressure Characteristics Chart

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5 Installation
5 1 Piping Example
5 2 Warning and precaution on installation
Warning
In case installing safety relief valve as safety device at outlet side, joint relief pipe at outlet of
safety relief valve and guide it to safety place where steam can relief out
Caution
( 1 ) Do not disassemble the valve unreasonably
*Disassembling the valve at your discretion may affect the original performance
( 2 ) Remove foreign matter and scales from the lines before installing the valve
*Failure to do so may prevent the valve from functioning correctly
( 3 ) Install a SY-24 strainer (Screen: 60 mesh) at the valve inlet side
*Failure to do so may hamper correct pressure control, which affects the original
performance
( 4 ) Install a safety relief valve at the valve outlet side for protection of equipments
*Failure to do so prevents problem detection, resulting in equipment damage
( 5 ) Install a pressure gauge at the inlet side of the valve
*Failure to do so may hamper correct pressure adjustment
( 6 ) When installing quick open and close valves, such as a solenoid valve, secure at least 3 m
from the valve
*Failure to do so may result in malfunction or drastically shortened service life
( 7 ) 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
( 8 ) Install the valve in proper direction of the fluid flow
*Failure to do so affect the performance
( 9 ) Do not apply excessive load, torque or vibration to the valve
*Doing so may result in malfunction or drastically shortened service life
( 10 ) Secure the necessary maintenance space at the installation site of the pressure reducing
valve (See Fig 1)
*In case there is not enough space for maintenance, pressure reducing valve cannot be
disassembled at the time of maintenance
( 11 ) The set pressure of safety relief valve must be higher than the set pressure of pressure
reducing valve
*In case reseating pressure of safety relief valve is lower than the set pressure of
pressure reducing valve, safety relief valve will continue to blow
( 12 ) Do not freeze pressure reducing valve
*Freezing may damage pressure reducing valve
( 13 ) Do not allow pipe adhesive materials to leak into pressure reducing valve
*In case the adhesive material is acquired in pressure reducing valve, it causes
malfunction
(14) Replace the factory-
installed plug at the pressure gauge joint with the pressure gauge
enclosed in the package
*The factory-installed plug is only for an airtightness test and it is not resistant to corrosion

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■EPDT-175d■
Nominal
size A B C
15A 245 105 120
20A 270 110 125
25A 290 135 135
32A 340 160 140
40A 420 175 160
50A 480 215 170
Fig 1
6 Operating Procedure
6 1 Warning and precaution on operation
Warning
( 1 ) Do not touch directly to pressure reducing valve with bare hands after flowing hot fluids
*Doing so may result in burns
( 2 ) Before flow the hot fluids in the pipe line, make sure that the fluids will not cause the
risks through the end of piping system and the pipes are connected tightly
*In case hot fluids blows out, it may result in burns
Caution
( 1 ) When opening the by-pass stop valve, ensure that the reduced pressure will not exceed
set pressure of safety relief valve
*In case reduced pressure exceeds set pressure of safety relief valve, the safety relief
valve operates and blows out the fluids
( 2 ) When operation is discontinued for a long period of time, completely purge fluid from
pressure reducing valve and piping system, and close the stop valve located up stream
and down stream of pressure reducing valve
*Water scales developed in the piping may cause erratic operation of pressure reducing
valve
6 2 Adjustment Procedure
GD-24 pressure reducing valve is set at 0 1MPa at the factory Change the set pressure as
appropriate Wrong or poor adjustment may cause hunting, scale buildup or water hammer, or
severely damage relevant parts Be sure to follow the following steps to complete proper
adjustment (Refer to the parts number in “2 2 Construction”)
1) Close the stop valves at both sides of the pressure reducing valve, and thoroughly purge the
system through the by-pass line, with the by-pass valve opening adjusted so that the safety
relief valve is not activated When completed, be sure to close the by-pass valve
2) Slowly open the inlet stop valve, then open the outlet stop valve slightly, allowing a trickle
to be discharged
3) Loosen the lock nut (11) and the sealed nut (17), and slowly turn the adjusting screw (10)
(clockwise to increase, counterclockwise to reduce) while observing the pressure gauge (19) on
the body (1)
4) Slowly open the outlet stop valve to its full-open position
5) After the adjustment, tighten the lock nut (11) and the sealed nut (17)

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7 Maintenance Procedure
Be aware of foreign materials because many of faults on pressure reducing valve are due to the
existence of foreign materials Please be reminded that our warranty does not cover damages
caused by foreign materials at the customer site Failure resulting from faulty pressure gauge,
clogged strainer and leakage from by-pass stop valve are phenomena kindred to failure of pressure
reducing valve Clogged strainer will decrease the secondary pressure and leakage from by-pass
pipe will increase the secondary pressure Before do the troubleshooting of pressure reducing valve,
check such symptom of the strainer and stop valve
7 1 Warning and precaution on maintenance and inspection
Warning
The pressure reducing valve shall be disassembled and inspected by qualified persons
( 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 ) To maintain the functions and performance of pressure reducing valve, perform
periodical inspection
*User should request to specialized dealer or manufacturer for such tasks
( 2 ) Pressure reducing valve should be disassembled and inspected by qualified person or
manufacturer
*Request the treatment to specialized dealer or manufacturer in case of any problems
( 3 ) During disassembling, internal fluid flows out Discharge it into a suitable container
Disassembling pressure reducing valve after all fluids have been discharged
*Fluid spills will contaminate surroundings
( 4 ) Close the stop valves before and after pressure reducing valve, and remove all foreign
matter and scales via the by-pass line before operation
*Failure to do so may cause the malfunction of pressure reducing valve
･Consumable parts and replacement period
Service life of consumable parts is dependent on the frequency and condition of usage Rough
indication of service life is given below
(Refer to the parts number in “2 2 Construction”)
Name of parts No Replacement period
Diaphragm (8) 3 years
O-ring (15)・(23) 3 years

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7 2 Troubleshooting
(Refer to the parts number in “2 2 Construction”)
Problem Cause Countermeasure
Reduced pressure
exceeds prescribed
level
1 Diaphragm (8) is damaged
2 Foreign matter is embedded in
the valve (4) and/or valve seat (5),
or else scratches exist
1 Replace the diaphragm (8)
2 Disassemble and remove the
foreign mater
If scratches exist, replace it
Pressure does not
rise to the desired
level
1 Screen (22) is clogged
2 Pressure gauge (19) malfunction
1 Disassemble and clean
2 Replace the pressure gauge (19)
Leakage
1 Loosen Bolt (16)
2 Loosen Cap (3)
3 Broken O-ring (15) for cap
1 Tighten Bolt (16)
2 Tighten Cap (3)
3 Replace O-ring (15) for cap
new one
Abnormal noise is
heard
1 The suspension metal (6) is in
incorrect position
1 Correct the position of the
suspension metal (6)
8 Exploded Drawing
･Part names shown in boxes are consumable parts