Piston Assembly for Sanitary Diaphragm Valve Actuators

Product Specifications

Technical details and manufacturing context for Piston Assembly

Definition

The piston assembly is a critical component within a sanitary diaphragm valve actuator, responsible for translating fluid pressure into controlled linear displacement. It consists of a piston, piston rod, seals, and associated hardware that work together to move the actuator stem, which in turn flexes the diaphragm to open or close the valve. In sanitary applications, this assembly is designed for cleanability, corrosion resistance, and reliable operation in hygienic processing environments. The assembly is typically constructed from stainless steel (AISI 316L) for the piston and rod, with PTFE and EPDM seals. The operating pressure range is 1.0–1.6 MPa, and the bore diameter ranges from 50–200 mm, with a stroke length of 10–100 mm. Operating temperature is -20 to 80°C, and piston speed should be kept between 0.1–0.5 m/s to avoid water hammer. Leakage rate at rated pressure is ≤0.1 cm³/min. Surface roughness of the piston is Ra 0.4–0.8 μm, critical for seal life. The piston material is 316L per ASTM A276, and the seal material is EPDM per FDA 21 CFR 177.2600. Weight ranges from 2.5–15 kg. These values are reference ranges and must be verified for the specific model and application. The assembly's design ensures cleanability and corrosion resistance, making it suitable for food, beverage, and pharmaceutical processing. Proper selection of materials and parameters is essential for reliable operation and long service life. Always consult the manufacturer for model-specific specifications and compliance with applicable standards.

Working Principle

When pressurized air or hydraulic fluid enters the actuator cylinder, it exerts force on the piston surface. This force causes the piston to move linearly along the cylinder bore. The piston rod transmits this motion to the actuator stem, which applies force to the diaphragm. The assembly's seals prevent fluid leakage while allowing smooth movement, with the piston's travel distance determining the valve's opening degree. The piston speed must be controlled within 0.1–0.5 m/s to prevent water hammer. The operating pressure range is 1.0–1.6 MPa, and the temperature range is -20 to 80°C. The piston's surface roughness (Ra 0.4–0.8 μm) is critical for seal life. The assembly's design ensures cleanability and corrosion resistance, making it suitable for hygienic processing environments.

Common Materials

Stainless Steel (AISI 316L), PTFE (Polytetrafluoroethylene), EPDM (Ethylene Propylene Diene Monomer)

Technical Parameters

Parameter	Typical range	Notes & selection driver
Bore Diameter	50–200 mm	Determines actuator thrust
Stroke Length	10–100 mm	Matches valve travel
Operating Temperature	-20–80 °C	Seals degrade above 80°C
Piston Speed	0.1–0.5 m/s	Higher speeds cause water hammer
Leakage Rate	≤0.1 cm³/min	At rated pressureISO 5208
Surface Roughness	Ra 0.4–0.8 μm	Critical for seal life
Piston Material	316L	Corrosion resistance for sanitary useASTM A276
Seal Material	EPDM	Food-grade, temperature resistantFDA 21 CFR 177.2600
Weight	2.5–15 kg	Affects handling and installation

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Components / BOM

Piston Part
Primary pressure-receiving component that converts fluid pressure to mechanical force

Material: Stainless Steel
Piston Rod Part
Connects the piston to the actuator stem and transmits linear motion

Material: Stainless Steel
Piston Seals Part
Prevent fluid leakage between piston and cylinder while allowing movement

Material: PTFE or EPDM
Wear Rings Part
Guide the piston within the cylinder and prevent metal-to-metal contact

Material: PTFE

Applied To / Applications

This component is essential for the following industrial systems and equipment:

Magnetorheological Damper

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Hydraulic Actuator Cylinder

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High Pressure Pump

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Brake Master Cylinder

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Linkage & Hydraulic Cylinders

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Hydraulic Climbing Cylinders

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Hydraulic Actuator / Compensation Cylinder

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Articulation Cylinders

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Tensioning Cylinder

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Manufacturers of Piston Assembly

3 companies list this product among what they make. Company figures are quoted from each company's own website; every card states where the relationship came from.

Better Petro China

Dongying, Shandong, CN

Also makes: Desanders/Desilters, Pressure Relief Valve, Hydraulic Power Unit and 9 more

Listed on the company's own website · profile compiled by CNFX from public sources

Listed there as: “Piston Assembly”
View source page ↗ betterpetro.com · checked 2026-09-16

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CHINA KOMAL INTERNATIONAL CO., LTD

Beijing, CN

Also makes: High Pressure Pump, Centrifugal Pump, Traveling Block and 9 more

Listed on the company's own website · profile compiled by CNFX from public sources

Listed there as: “Piston Assembly”
View source page ↗ chinakomal.com · checked 2026-09-16

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Dezhou Boru Petroleum Machinery Manufacturing Co.,Ltd

Dezhou, Shandong, CN

Also makes: Valve Assembly, Pump Fluid End (Wet End), Piston & Rod

Listed on the company's own website · profile compiled by CNFX from public sources

Listed there as: “A-1700-PT Piston Assembly”
View source page ↗ brmudpumpparts.com · checked 2026-09-03

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Manufacturer listings support early research and capability understanding. They are not certification, ranking, or transaction guarantees.

Compiled and source-reviewed by the CNFX editorial team. Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review · Page last updated 16 September 2026

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

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Frequently Asked Questions

What materials are used in the piston assembly?

The piston and rod are typically made of stainless steel AISI 316L, while seals are made of PTFE and EPDM. The seal material is EPDM per FDA 21 CFR 177.2600 for food-grade applications.

What is the operating pressure range?

The operating pressure range is 1.0–1.6 MPa. Always verify the exact range for your specific model.

How does temperature affect the assembly?

The operating temperature range is -20 to 80°C. Seals degrade above 80°C, so it is crucial to stay within this range to ensure seal integrity and reliable operation.

What is the leakage rate at rated pressure?

The leakage rate at rated pressure is ≤0.1 cm³/min. This ensures minimal fluid loss and proper sealing performance.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records.

Preliminary Technical Classification

This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

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pressure:	0 to 10 bar (gauge)
flow rate:	Dependent on valve size and actuator stroke
temperature:	-20°C to 150°C
slurry concentration:	Up to 40% solids by weight (particle size < 100 microns)

Piston Assembly

Product Specifications

Applied To / Applications

Industrial Ecosystem & Supply Chain Structure

Application Fit & Sizing Matrix

Reliability & Engineering Risk Analysis

Compliance & Manufacturing Standards

Manufacturers of Piston Assembly

Procurement Evaluation Criteria

Supply Chain Compatible Machinery & Devices

Frequently Asked Questions

What materials are used in the piston assembly?

What is the operating pressure range?

How does temperature affect the assembly?

What is the leakage rate at rated pressure?

Data Basis

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