Working Principle And Material Selection Of Sanitary-grade Union-type Pressure Relief Safety Valve

A sanitary pressure relief valve controls overpressure through a calibrated spring that balances process pressure. Increasing spring compression raises the set pressure, while reducing compression lowers it. For a stainless steel union-style installation, accurate setting also depends on seat sealing, pressure range, temperature, and installation conditions.

How Spring Force Controls Pressure

A hygienic pressure relief valve stays closed during normal operation because spring force holds the sealing element against its seat. When process pressure reaches the set point, pressure force overcomes the spring load and opens the discharge path.

The operating sequence is straightforward:

Spring Balance and Valve Response

1. Normal pressure: Spring force keeps the valve closed.
2. Pressure rise: Process pressure acts against the sealing element.
3. Set pressure reached: The valve starts to open at the calibrated pressure.
4. Pressure release: Discharge lowers system pressure and allows reseating.

A referenced design uses a spring compression nut for pressure adjustment and lists a control range of 0.5–6 bar. Its stated working pressure is up to 6 bar, with medium temperatures from -10°C to 120°C.

Why Calibration Must Match the Process

A sanitary prv should be adjusted from the actual operating pressure and required protection limit. The set point needs to remain above normal process pressure while staying within the permitted range of the protected equipment.

Spring compression: Changes the force holding the valve closed.
Set pressure: Determines when pressure relief begins.
Temperature: Can affect spring and seal performance.
Medium: Liquid and gas service can require different design checks.

A sanitary safety valve should not be adjusted only from a scale or nominal rating. Calibration should also consider pressure measurement accuracy, installation conditions, and the applicable safety requirements.

Stainless Steel and Sealing Design

The referenced model uses SS304 or SS316L construction with food-grade rubber sealing. It lists DIN, 3A, SMS, and ISO standards, with a stated surface treatment of Ra 0.8 μm. The specification also covers liquid and gas media.

SS316L can suit service with higher corrosion exposure, while SS304 may fit general hygienic applications. Seal selection should match the process medium, temperature, cleaning chemicals, and pressure cycles.

Connection and Installation

A sanitary safety relief valve should be installed with an unobstructed inlet and a discharge route sized for the required relief condition. Connection selection should also consider maintenance access and the loads transmitted from the piping.

For union-style piping, proper alignment reduces mechanical stress on the valve body. Excessive external loading can affect sealing and movement, so the valve should not be forced into alignment during assembly.

A sanitary pressure relief valve should remain accessible after installation. Pressure adjustment, inspection, and servicing should be possible without removing nearby equipment.

Calibration and Maintenance Checks

Before commissioning, calibration should take place under controlled conditions. A sanitary safety valve is a protective device, so its set pressure should be traceable to the process design requirement.

Recommended checks include:

• Verify the pressure gauge against a reference.
• Confirm the set point after adjustment.
• Inspect the seat for residue or damage.
• Check spring movement and adjustment hardware.
• Confirm the discharge route is unobstructed.

Periodic inspection is required because spring condition, deposits, sealing surfaces, and process changes can alter valve response.

Selecting the Right Configuration

The correct valve depends on protected equipment, normal operating pressure, set pressure, medium, temperature, connection type, and cleaning conditions. A sanitary safety relief valve should then be calibrated under conditions that reflect actual service.

When these factors are considered together, spring compression becomes the control point connecting pressure protection, sealing behavior, and repeatable operation in a hygienic process system.

Sanitary Stainless Steel Pressure Relief Safety Valve With Union Ends

• We can supply Sanitary Tri Clamp Pressure Relief Valve, Hygienic Butt Weld Pressure Release Safety Valve, Sanitary Thread Safety Valve.
• The series safety valve is to adjust the spring compression nut to calibrate a particular pressure.the calibration of pressure is to fix the maximum pressure to avoid the equipment damage. In the normal working operating pressure,the valve is closed.When the system pressure exceeds the fsysterm and the equipment.The valve is with start the open device for the CIP cleaning of the safety valve and the piping.
• The safety valve is a special valve through a rigorous calibration,but to make the valve more realistic operating conditions, so the conditions shoud be as mush as possible the scene of the valve and then parity.

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