Back Pressure Regulator: Flow Coefficient (Cv) 0.1 to 10.0

Q: What is the difference between a back pressure regulator and a pressure relief valve?

A back pressure regulator maintains constant upstream pressure by modulating flow continuously, while a pressure relief valve opens fully at a set pressure to prevent overpressure and then closes. BPRs are for process control, PRVs are for safety protection.

Q: How do you select a back pressure regulator for a continuous flow reactor?

Consider upstream pressure requirements, flow rate, fluid compatibility (corrosiveness, abrasiveness), temperature range, required accuracy, and response time. Material selection (especially for wetted parts) is critical for chemical resistance.

Q: What maintenance is required for back pressure regulators?

Regular inspection of diaphragms/seals for wear, cleaning of trim components to prevent fouling, calibration checks for pressure accuracy, and verification of response characteristics. Maintenance frequency depends on service conditions.

Component Specifications

Definition

A back pressure regulator (BPR) is an automatic control valve designed to maintain a constant pressure at its inlet (upstream) by adjusting the flow resistance at its outlet (downstream). In continuous flow reactor systems, it ensures stable reaction conditions by compensating for pressure fluctuations from pumps, temperature changes, or flow variations. Unlike pressure relief valves that open at set pressures, BPRs modulate continuously to maintain precise upstream pressure control.

Working Principle

The back pressure regulator operates on a force-balance principle where upstream pressure acts against a spring-loaded diaphragm or piston. When upstream pressure exceeds the setpoint, the valve opens to release fluid, reducing pressure. When pressure drops below the setpoint, the valve closes to increase pressure. This continuous modulation maintains constant upstream pressure regardless of downstream changes. In continuous flow reactors, it typically uses a dome-loaded or spring-return mechanism with feedback control.

Materials

Body: 316L stainless steel (standard), Hastelloy C-276 (corrosive applications); Diaphragm/Seals: PTFE, FKM (Viton), EPDM; Spring: Inconel 718; Trim: Tungsten carbide, Ceramic (abrasive services); Gaskets: Graphite, PTFE

Technical Parameters

Parameter	Typical range	Notes & selection driver
Accuracy	±1% of setpoint
Leakage Class	ANSI/FCI 70-2 Class IV or better
Response Time	<100 ms
Pressure Range	0-100 bar (standard), up to 400 bar (high-pressure)
Connection Types	1/4" to 1" NPT, ISO, or flange connections
Temperature Range	-20°C to 200°C (standard), up to 400°C (high-temp)
Flow Coefficient (Cv)	0.1 to 10.0

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

Standards

ISO 4126-1, ASME B16.34, DIN 3381, API 526

Parent Products

This component is used in the following industrial products

Continuous Flow Reactor System

A modular, automated chemical processing system designed for continuous flow synthesis of chemical products.

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Engineering Analysis

Risks & Mitigation

Pressure overshoot/undershoot causing reactor instability
Material incompatibility leading to corrosion/contamination
Diaphragm failure causing loss of pressure control
Fouling/clogging in trim affecting accuracy
Improper sizing causing flow limitations

FMEA Triads

Trigger: Diaphragm fatigue or chemical degradation
Failure: Loss of pressure control leading to reactor pressure fluctuations
Mitigation: Use chemically compatible diaphragm materials, implement regular inspection/replacement schedules, install redundant pressure sensors

Trigger: Contaminant buildup in valve trim
Failure: Reduced accuracy and response time, potential clogging
Mitigation: Install upstream filtration, use self-cleaning trim designs, implement regular maintenance cleaning

Trigger: Spring relaxation or corrosion
Failure: Drift in set pressure over time
Mitigation: Use corrosion-resistant spring materials (Inconel), implement periodic calibration, use digital pressure controllers with feedback

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

Pressure control accuracy: ±1% of setpoint or better; Leakage: ≤0.01% of Cv at rated pressure

Test Method

ASME PTC 25 for pressure relief devices, ISO 4126 for safety valves, manufacturer's calibration procedures using deadweight testers or precision pressure calibrators

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

Verify equipment lists, process limits, capacity, and representative production evidence.

Inspection readiness

Confirm test methods, calibrated equipment, sampling plans, and traceable reports.

Supplier transparency

Check the legal entity, factory address, ownership, certifications, and direct contacts.

CNFX does not score or rank suppliers. Buyers must verify all claims and documents with the legal manufacturer before ordering.

Manufacturers of Back Pressure Regulator

2 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.

Fitok Group

Beijing, CN

Also makes: Directional Control Valve, Sample Handling System, Pressure Relief Valve and 9 more

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

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Hikelok

Chengdu, Sichuan, CN

Also makes: Pressure Regulator, Diaphragm Valve, Sample Intake System and 9 more

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

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

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Frequently Asked Questions

What is the difference between a back pressure regulator and a pressure relief valve?