Description
Overview
The ControlAir Type 625 Volume Booster is a 1:1 signal-to-output pneumatic relay designed to improve control valve performance by increasing airflow to diaphragm and piston actuators. Ideal for large-volume actuators, the Type 625 increases throttling speed and provides faster valve response while maintaining proportional output pressure for precise, stable control.
An integral adjustable bypass valve and fixed deadband allow small incremental downstream pressure adjustments without opening the main booster valve. The bypass can also be adjusted to tune dynamic response, helping provide stable and reliable operation across a wide range of actuator sizes and demanding industrial applications.
The Type 625 combines fast response, high accuracy, tight shutoff, and integrated air filtration in a rugged aluminum housing. A soft valve seat eliminates leakage during steady-state operation, while an integrated 100-mesh filter helps protect internal components from dust and contaminants.
Key Features
- 1:1 signal-to-output pressure ratio
- Designed for diaphragm and piston actuators
- Fast response improves actuator movement and reduces lag
- Integral adjustable bypass valve
- Fixed deadband for stable operation
- Bypass allows small signal changes without opening the primary booster valve
- Adjustable bypass enables dynamic response tuning
- Soft valve seat provides tight shutoff
- Eliminates leakage during steady-state operation
- High accuracy and sensitivity to small signal changes
- Integrated 100-mesh air filter protects internal components
- Maximum forward Cv of 1.5
- Maximum exhaust Cv of 1.5
- 1/4″ NPT porting
- Aluminum construction
- Low Temperature option available
- Expanded Temperature option available
- ATEX 2014/34/EU option available
Performance Characteristics
- Signal/Output Ratio: 1:1
- Maximum Supply Pressure: 150 psig (10.0 bar)
- Maximum Signal Pressure: 150 psig (10.0 bar)
- Temperature Range: -40°F to 200°F (-40°C to 93°C)
- Maximum Forward Cv: 1.5
- Maximum Exhaust Cv: 1.5
- Exhaust Capacity: 15 SCFM (425 Nl/min) at 5 psig above a 20 psig setpoint
- Output Accuracy: 1.0% of 100 psi output span
- Hysteresis: 1% maximum
- Signal Port: 1/4″ NPT
- Supply/Output Ports: 1/4″ NPT
- Exhaust: Four 0.23″ vents
- Weight: 1.25 lbs (0.56 kg)
The Type 625 increases the volume of air available to the actuator while maintaining a proportional 1:1 relationship between input signal and output pressure. This allows a relatively low-flow pneumatic control signal to command a large-volume actuator with faster response and reduced lag. The flow curves provided in the specification sheet illustrate regulated pressure versus flow performance at both 100 psig and 150 psig supply conditions.
How to Select the Right Configuration
Selecting the correct Type 625 configuration depends primarily on the operating temperature, installation requirements, and hazardous-area requirements of the application.
- Select the standard Type 625 for applications operating from -40°F to 200°F (-40°C to 93°C)
- Select the Low Temperature option for applications requiring operation down to -62°F (-52°C)
- Select the Expanded Temperature option for applications requiring operation up to 284°F (140°C)
- Select the ATEX option when ATEX 2014/34/EU compliance is required
- Use the optional mounting bracket when dedicated bracket mounting is required
When applying the Type 625 to a control valve, consider actuator volume, required stroking speed, available supply pressure, and desired dynamic response. The integral bypass valve can be adjusted to balance fast actuator movement with stable control.
For additional guidance:
Applications
The Type 625 is designed for pneumatic control systems where a low-flow control signal must operate a larger-volume actuator quickly and accurately. Its high flow capability, 1:1 pressure ratio, adjustable bypass, and fast response make it particularly well suited for improving control valve actuator performance.
- Control valve actuation
- Diaphragm actuators
- Piston actuators
- Large-volume pneumatic actuators
- Valve positioning systems
- I/P transducer volume boosting
- Pneumatic positioner volume boosting
- Fast-response control valve applications
- Process control systems
- Industrial automation
- OEM pneumatic systems
The Type 625 is especially useful when the control signal provides the required pressure command but does not have sufficient airflow to move the actuator at the desired speed.
Models & Configurations
Type 625 Ordering Structure
625-BA[Options]
Standard Configuration
- Housing Material: Aluminum
- Porting: 1/4″ NPT
- Signal/Output Ratio: 1:1
Available Options
- L = Low Temperature: -62°F to 194°F (-52°C to 90°C)
- P = Expanded Temperature: -55°F to 284°F (-48°C to 140°C)
- X = ATEX 2014/34/EU
Accessories
- Mounting Bracket, Zinc-Plated Steel: P/N 449-542-061
Technical Resources
FAQs
What is the Type 625 Ratio Relay Volume Booster used for?
The Type 625 increases airflow from a low-flow pneumatic control signal to diaphragm or piston actuators, helping large-volume actuators move faster while maintaining a proportional 1:1 signal-to-output pressure relationship.
What is the signal-to-output ratio of the Type 625?
The Type 625 has a 1:1 signal-to-output ratio, providing output pressure proportional to the input signal while increasing the volume of air available to the actuator.
What does the adjustable bypass valve do?
The integral adjustable bypass valve allows small incremental signal changes to adjust downstream pressure without opening the primary booster valve. It can also be adjusted to tune dynamic response for stable actuator operation.
What are the maximum supply and signal pressures?
The maximum supply pressure and maximum signal pressure are both 150 psig (10.0 bar).
What is the flow coefficient of the Type 625?
The Type 625 has a maximum forward Cv of 1.5 and a maximum exhaust Cv of 1.5, providing high pneumatic flow capacity for faster actuator response.
How accurate is the Type 625?
The Type 625 provides output accuracy of 1.0% of a 100 psi output span with maximum hysteresis of 1%.
Does the Type 625 provide tight shutoff?
Yes. The soft valve seat design provides tight shutoff and eliminates leakage during steady-state operation.
Does the Type 625 include air filtration?
Yes. The Type 625 incorporates an integrated 100-mesh filter to help protect internal components from dust and contaminants.
What temperature options are available?
The standard temperature range is -40°F to 200°F (-40°C to 93°C). A Low Temperature option provides a range of -62°F to 194°F (-52°C to 90°C), while the Expanded Temperature option provides a range of -55°F to 284°F (-48°C to 140°C).
Is an ATEX version of the Type 625 available?
Yes. An ATEX 2014/34/EU option is available for applications requiring this certification.
