Design and Application of Plastic Diaphragm Valves

Plastic diaphragm valves are specially designed valves widely used for controlling fluid flow, especially when dealing with corrosive or viscous media. Their unique feature is the use of a flexible diaphragm (usually made of rubber or plastic materials) as the mechanism to open and close the fluid passage. The body of diaphragm valves is typically made from corrosion-resistant plastic materials such as PVC (Polyvinyl Chloride), CPVC (Chlorinated Polyvinyl Chloride), PP (Polypropylene), and PVDF (Polyvinylidene Fluoride), making them highly suitable for use in chemical processing, water treatment, food and beverage, biotechnology, and pharmaceutical industries.

Advantages of plastic diaphragm valves include excellent corrosion resistance, good sealing capabilities, ease of operation and maintenance, and the ability to handle fluids with solid particles without clogging. Therefore, they are particularly important in applications where strict control of fluid purity and avoidance of cross-contamination are required.

Moreover, the design of diaphragm valves facilitates convenient replacement of the diaphragm or maintenance, as these tasks can often be performed without removing the valve from the pipeline system, significantly reducing maintenance time and costs.

Specifications
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Specification

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Double union diaphragm valve
Socket Type Diaphragm Valve
Flange Type Diaphragm Valve
Pneumatic Type Diaphragm Valve
885 Y Type Diaphragm Valve

A double union diaphragm valve on white background.

A dimension drawing of double union diaphragm valve.

Table 1: Size Tables of Double Union Diaphragm Valve
Nominal Diameter	d (φ)	A (mm)	L (mm)	I (mm)	H (mm)
DN15	φ 20	65	140	18.5	99
DN20	φ 25	65	142	21	99
DN25	φ 32	94	176	26	136
DN32	φ 40	94	180	28	136
DN40	φ 50	118	245	37	178
DN50	φ 63	118	258	37	178
DN65	φ 75	189	343	42.5	240
DN80	φ 90	189	365	50	240
DN100	φ 110	239	568	69	277

A socket type diaphragm valve on white background.

A dimension drawing of socket type diaphragm valve.

Table 2: Size Tables of Socket Type Diaphragm Valve
Nominal Diameter	d (φ)	A (mm)	L (mm)	I (mm)	H (mm)
DN15	φ 20	65	97	16	99
DN20	φ 25	65	101	18	99
DN25	φ 32	94	124	22	136
DN32	φ 40	94	132	26	136
DN40	φ 50	118	175	27	178
DN50	φ 63	118	185	32	178
DN65	φ 75	189	272	44	240
DN80	φ 90	189	284	50	240
DN100	φ 110	239	340	61	277

A flange type diaphragm valve on white background.

A dimension drawing of flange type diaphragm valve.

Table 3: Size Tables of Flange Type Diaphragm Valve
Nominal Diameter	φ	d (mm)	A (mm)	L (mm)	H (mm)
DN15	φ 20	95	65	112	99
DN20	φ 25	105	65	120	99
DN25	φ 32	115	94	140	136
DN32	φ 40	140	94	147	136
DN40	φ 50	150	118	197	178
DN50	φ 63	165	118	206	178
DN65	φ 75	185	189	285	240
DN80	φ 90	200	189	312	240
DN100	φ 110	220	239	366	277

A pneumatic type diaphragm valve on white background.

A dimension drawing of pneumatic type diaphragm valve.

Table 4: Size Tables of Pneumatic Type Diaphragm Valve
Nominal Diameter	d (mm)	I (mm)	L (mm)	H (mm)
DN15	20	21	140	194
DN20	25	21	142	196
DN25	32	26	176	262
DN32	40	28.5	180	272
DN40	50	37	245	380
DN50	63	37	258	390
DN60	75	42	343	394
FN80	90	50	365	406
DN100	110	60	568	487

Working principle

Close the valve: Lead the control pressure source (water or air source, pressure equal to or greater than the water pressure) to the control chamber on the diaphragm, and the diaphragm pushes the valve seat through the valve stem to intercept the incoming water and close the valve.

Open the valve: When the pressure in the upper chamber of the diaphragm is relieved, the water pushes the valve stem open under its own pressure, opening the valve and forming a passage for the fluid to flow through.

Technical features

The upper and lower dual chamber design is adopted, and the control water flow is independent of the fluid chamber. Through the upper and lower pressure ends, the valve can flexibly controlled to open or close at will. The choice of pressure source is also more diverse, which can be hydraulic or pneumatic.

Working Pressure: 0.1-0.8 MPa
Working Temperature: 4–50 °C
Body Material: PA, UPVC
Caliber: DN15 – DN100
Connection method:
- DN15 – DN50 (Socket Connection)
- DN65 – DN100 (Flange Connection)

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