Yoshitake GD-21 Manuel utilisateur

EPDT-255b

MODEL GD-21

Differential Pressure Regulating 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 references.

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. Usage ofthe product ·················································· 1

2. Features·································································· 1

3. Specifications···························································· 1

4. Dimensions and Weight ·············································· 2

5. Operation································································· 3

6. Nominal Size Selection··············································· 4

6.1 Nominal sizes selection chart·································· 4

6.2 Calculation formula for Cv value······························ 4

7. Installation································································ 5

7.1 Precautions for installation ····································· 5

7.2 Piping example···················································· 6

8. Operating Procedure·················································· 7

8.1 Precautions for operation······································· 7

8.2 Precautions for air vent ········································· 7

8.3 How to use air vent··············································· 7

9. Maintenance····························································· 7

9.1 Precautions for disassembly and maintenance··········· 7

9.2 Disassembly······················································· 8

9.3 Reassembly························································ 8

9.4 Precautions for reassembly···································· 9

10. Troubleshooting······················································· 9

11. Exploded Drawing···················································10

Warranty Information

EPDT-255b

1. Usage of the Product

The GD-21 is used for pump in a closed circuit of air-conditioning or heating equipment in mid-rise and

high-rise buildings. While an open circuit requires a primary pressure reducing valve as relief valve for pump,

a closed circuit requires a differential pressure regulating valve since it is necessary to operate the pump at a

constant flow rate no matter how back pressure fluctuates.

2. Features

1. The product is the most suitable for pump in a closed circuit.

2. Since the main valve features a single-seat valve and a disc, leakage is prevented when closed.

3. Specifications

Model GD-21

Application Cold and hot water

Nominal size 15A-80A 100A-150A

Regulating differential pressure

(A) 0.05-0.25 MPa

(B) 0.26-0.7 MPa (A) 0.05-0.25 MPa

(B) 0.26-0.5 MPa

Fluid temperature 5-80˚C

Material

Body Ductile cast iron

Valve seat Stainless Steel or Bronze

Valve disc NBR

Diaphragm NBR

Connection JIS 10K FF Flanged

Inside surface treatment of body

Electrodeposition coating

Caution

Please confirm that the indications on the product correspond with the

specifications of the ordered model before use.

* If they are different, do not use the product and contact us.

■Flow rate characteristics chart

* Accumulation

Set range (MPa) Accumulation (MPa)

0.05-0.25 0.05 or below

0.26-0.7 0.105 or below

* Accumulation

Adjusteddifferentialpressure

Flow rate

Differential pressure to

determine rated flow

Rated flow rate

Shut-off pressure drop 10%

of set pressure (gauge pressure)

(Min. value 0.02 MPa)

Min.adjustableflowrate

Set differential pressure

EPDT-255b

4. Dimensions and Weight

(mm)

Nominal size

L H H1b Weight (kg)

15A 145 298 57 36 8.3

20A 150 298 57 36 8.3

25A 150 320 67 36 10.1

32A 195 400 76 48 17.4

40A 195 400 76 48 17.4

50A 195 414 81 48 19.3

65A 270 572 110 63 40.1

80A 270 597 125 63 43.8

100A 308 665 143 68 70.1

125A 380 866 179 115 144.1

150A 400 936 204 115 173.1

EPDT-255b

5. Operation

Size 15A-50A

No.

Parts Name

Body

Spring Chamber

Retainer

Retainer Guide

Spindle

Valve Seat

Valve

Diaphragm

Spring Plate

Adjusting Spring

Adjusting Screw

Lock Nut

Cap

U Nut

Conductor Pipe

Air Vent

Bolt

O Ring

•The shapes differentiate slightly depending on the nominal size.

When fluid flows into the product, the inlet pressure is applied to the bottom side of the

diaphragm [8] via the conductor pipe [16] and the outlet pressure is applied to the top side of

the diaphragm [8] via outlet pressure sensing port.

The product is kept closed while the pressure difference between before and after the product

is less than the set pressure.

When the pressure difference goes over the set pressure, the load of the differential pressure

between the top and bottom sides of the diaphragm [8] overcomes the load of the adjusting

spring [11] to lift up the valve [7] apart from the valve seat [6], opening the product.

When the pressure difference falls below the set pressure, the product closes again so that

the pressure difference between before and after the product can be kept at constant level.

Outlet pressure

sensing port Rc 3/8

EPDT-255b

6. Nominal Size Selection

6.1 Nominal size selection chart (For water)

[Example]

When selecting the nominal size of a differential pressure regulating valve with differential pressure (P) of

0.2 MPa and flow rate (V) of 5.5 m3/h, find the intersection point (a) of differential pressure (P) and the flow

rate (V).

Since the intersection (a) lies between nominal sizes 25A and 32A, select the larger one, 32A.

6.2 Calculation formula for Cv value

■ Cv value

Nominal size

15A

20A

25A

32A

40A

50A

65A

80A

100A

125A

150A

Cv value

1.5 2.7

4 8.5 11 14 23 32.5

48 75 108

■ Calculation formula for Cv value

P1: Inlet pressure [MPa･A]

P2: Outlet pressure [MPa･A]

P: P1- P2[MPa]

G : Specific gravity (relative to water)

V : Max. liquid flow rate [m3/h]

Cv : Cv value of each nominal size

P: Differential pressure (MPa)

Nominal size

V: Flow rate (m

/h)

V: Flow rate (m

/h)

(a)

PGV365.0

Cv ∆

EPDT-255b

7. Installation

7.1 Precautions for installation

Caution

1. As the product is heavy, support it securely by lifting device while installation.

* Failure to follow this notice may result in bodily injury due to a drop accident.

2. Do not disassemble the product unless it is necessary.

* Disassembly may prevent the product from functioning properly.

3. Be sure to remove foreign substances and scales from the piping before connecting the product.

* Foreign substances and scales may prevent the product from functioning properly.

4. Install the product vertically to the horizontal piping. If installing it to a vertical piping is inevitable

due to limited space, the product can be installed to the vertical piping as long as its size is less

than 100A.

* Do not install the product of 100A or larger to a vertical piping.

5. Be sure to install pressure gauges to both the inlet and outlet sides of the product. In addition,

install strainer and bypass line to the piping around the product.

* Failure to follow this notice may hamper correct pressure adjustment.

6. Be sure to install a strainer (60-80 mesh) at the inlet side of the product.

* Foreign substances or scales may prevent the product from functioning properly.

7. Quick operating valve shall be installed more than 3 meters away from the product.

* Failure to follow this notice may result in malfunction or a drastically shortened service life of the

product.

8. Do not apply excessive load, torque or vibration to the valve when piping.

* Failure to follow this notice may result in malfunction or a drastically shortened service life of the

product.

9. Place a drain pipe between the stop valve and the product for easier maintenance and

inspections.

* Failure to follow this notice may cause fluid spill when disassembling.

* Guide the drain pipe to a drain ditch if there is a risk of contamination on the surroundings due to

the fluid spill.

10. Install a needle valve to the outlet side of the product and plumb it to the pressure sensing pipe

using copper piping.

* Failure to follow this instruction hampers correct pressure adjustment.

(1) Joint for the outlet pressure sensing is not included with the product package.

(2) Secure the space specified in the table below (H2) since it is required for maintenance and inspection.

H2indicates the required height above the horizontal center line of the piping (see Fig. 1 below).

■ Space required for disassembly (mm)

Nominal size

15A 20A 25A 32A 40A 50A 65A 80A 100A

125A

150A

H2500 500 500 650 650 650 800 800 1000

1200

1400

Fig. 1 Space required for disassembly

EPDT-255b

Two-way

valve

Two-way

valve

Air-conditioning

equipment

Air-conditioning

equipment

Pump Freezer or

heat source

Supply

header

Return

header

SU-20

Strainer

GD-21

SU-20

Strainer

Needle

valve*

Approx. 1000 mm

Outlet pressure

sensing port Rc 3/8

* Install a needle valve to the outlet side of the

product and plumb it to the pressure sensing

pipe using copper piping

7.2 Piping example

Fig. 2

Fig. 3

EPDT-255b

8. Operating procedure

8.1 Precautions for operation

Warning

Do not touch the product with bare hands when the fluid has a high-temperature.

* Failure to this notice may scald your skin.

Caution

1. Before leading fluid into the product, close the stop valves before and after the product and

remove all foreign substances or scales via the bypass line.

* Foreign substance or scales may prevent the product from functioning properly.

2. Before leaving the product not operated for a long time, discharge the fluid inside of the product

and piping completely, and close the stop valves before and after the product.

* Failure to follow this notice may cause malfunction due to rust generated inside the product and

piping, or result in damage due to freezing.

* The fluid can be drained out of the product efficiently with the air vent valve (see “8.2 Precaution

for air vent”).

3. Pressure regulation of the product shall be performed while the fluid running. To increase the set

differential pressure, loosen the lock nut [13], and then slowly turn the adjusting screw [12]

clockwise. To decrease the set differential pressure, slowly turn the adjusting screw [12]

counterclockwise.

* The fluid leaks if the cap [14] is removed. In this case, use a waste cloth to wipe it out.

4. Remove air accumulated in top and bottom sides of diaphragm using the air vents in accordance

with the procedures described in “8.3 How to use air vent.”

* Air accumulated in the top and bottom sides of the diaphragm may cause malfunction of the

product.

8.2 Precautions for air vent

Warning

Do not stand in front of the air vent valve during use.

* Failure to follow this notice may result in scalds or bodily injury due to blow-off of

the fluid inside.

Caution

Do not rotate the air vents more than 1/2 turn when use.

* Failure to follow this notice may make the air vents detached from the body. In this

case, the air vents may not be reattached.

8.3 How to use air vent

(1) Rotate the screw of the air vent [17] counterclockwise to loosen it in order to discharge air.

(2) Rotate the screw of the air vent [17] clockwise to the original closed position after discharging air.

9. Maintenance

9.1 Precautions for disassembly and maintenance

Warning

1. Disassembling and inspections must be performed by experienced professional or valve manufacturer.

2. Before disassembly or inspection, completely release internal pressure of the product, piping and

equipment. When the fluid is hot, cool down the product to the condition that it can be touched with bare

hands.

* Residual pressure may cause bodily injury or scalds and may contaminate surroundings of the

product.

EPDT-255b

U nut

[15]

Spring plate [9]

Spindle [5]

Bolt [18]

Retainer guide [4]

9.2 Disassembly

(1) Release the internal pressure from the piping completely, and make sure that the pressure gauge

shows that the pressure is zero.

(2) Remove the cap [14] and slightly loosen the lock nut [13], and then turn the adjusting screw [12]

counterclockwise so that the adjusting spring [11] can be in no load condition.

(3) Remove the spring chamber [2] by unscrewing the bolt [19], and then take out the adjusting spring

[11] and the spring plate [10].

(4) Remove the diaphragm [8] by fixing the spindle [5] and loosening the U nut [15].

(5) To remove the retainer [3], by loosening the bolt [18] and pulling out the retainer guide [4] together

with the retainer [3].

If the retainer guide [4] is difficult to be removed, do as indicated in Fig. 4 or Fig. 5 below

Nominal size 15-50A

To remove the retainer guide [4] easily, reattach the spring plate [9] and U nut [15] to the spindle [5], then

pull up the spring plate [9].

Fig. 4

Nominal size 65-150A

To remove the retainer guide [4] easily, screw the bolt [18] to the retainer guide [4] and pull them out. (See

Fig. 5)

Fig. 5

9.3 Reassembly

To reassemble the product, take reverse procedure to disassembly.

EPDT-255b

9.4 Precautions for reassembly

Caution

1. Make sure that there are no flaws on the diaphragm [8], the valve seat [6] and the valve [7].

* Flaws on them may prevent the product from functioning properly.

2. Apply silicon grease to the O-ring [20] after confirming that there are no flaws on it.

* Without silicon grease, the O-ring may be torn.

3. Confirm that the lip of the diaphragm [8] is fitted in the grooves on the body [1], and then attach the

spring chamber [2].

* Failure to follow this notice may prevent the product from functioning properly.

4. There should be a gap between the retainer guide [4] and the body [1] when properly assembled.

Tighten the bolts evenly to avoid over-tightening them.

10. Troubleshooting

Trouble Cause Remedy

Excessive leakage

Adjustment is

impossible.

Foreign substances stuck

between valve [7] and valve seat

[6]. Or damage on valve [7]

and/or valve seat [6].

Disassemble and clean, or replace.

Damage on diaphragm [8]

and/or O

ring.

Replace diaphragm [8] and/or O

ring

[20]

Nominal size i

s too small for the

specifications.

Replace the product

to obtain proper

nominal size (see “6.1 Nominal size

selection chart

”

Pressure gauge is out of order.

Replace.

Abnormal

sound is

observed

Air

induced problem occurs.

Install

exhaust equipment.

Nominal size is too large for the

specifications.

Replace the product

obtain

proper

nominal size (see “6.1 Nominal size

selection chart”).

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