Description
Overview
The ControlAir Mite 70 Air Relay is a compact, snap-acting pneumatic control relay designed to monitor an increasing or decreasing air or gas signal and switch immediately when the adjustable trip point is reached. When tripped, the relay vents one output port to atmosphere while locking pressure in a second output line.
The tripped state is held indefinitely until the control signal returns to the proper operating condition and the manual reset button is pressed. The trip point is adjustable from 1 to 100 psig using a simple screw-stem adjustment, and the relay can also be tripped on demand by a separate remote pneumatic signal.
Its passive pneumatic design, rugged construction, and crisp repeatability make the Mite 70 well suited for safety, alarm, shutdown, and actuator-control applications where reliable pneumatic decision-making is required without electrical power.
Key Features
- Snap-acting pneumatic control relay
- Trips on either an increasing or decreasing control signal
- Adjustable trip point from 1 to 100 psig
- Manual reset maintains the tripped condition until intentionally restored
- Vents one output port when tripped
- Locks pressure in a second output line when tripped
- Separate remote pneumatic trip connection
- Crisp, repeatable switching action
- Compact design for high-density installations
- Passive pneumatic operation requires no electrical power
- Suitable for air or compatible gas service
- 100 psig maximum pressure rating
- Broad operating temperature range
- Rugged aluminum construction
- Designed for critical safety and emergency process-control functions
Performance Characteristics
- Trip Function: Increasing or decreasing pneumatic signal
- Adjustable Trip Range: 1 to 100 psig
- Maximum Pressure Rating: 100 psig (7 bar)
- Operating Temperature Range: -40°F to 180°F (-40°C to 82°C)
- Port Connections: Tapped for 1/4″ NPT with 1/8″ internal ports
- Approximate Dimensions: 2.5″ diameter × 3.5″ high
- Weight: 1.2 lb (0.55 kg)
- Body Material: Aluminum
- Other Materials: Plated steel, neoprene, brass, and stainless steel
- Reset Method: Manual push-button reset
- Remote Trip: Pneumatic remote-trip connection
- Output Action: One output locks pressure while the other vents when tripped
During normal operation, the variable instrument-air signal is monitored at the control port. When the signal crosses the selected trip point, the internal snap-acting mechanism changes state immediately. One output traps the existing downstream pressure, while the other output opens to atmosphere. The relay remains latched until the monitored signal is restored and the reset button is pressed.
How to Select the Right Configuration
Selecting the correct Mite 70 configuration depends on whether the relay must respond to an increasing or decreasing signal, the expected signal-pressure range, the preferred reset-button length, and whether the trip signal is above or below 50 psig.
- Select an increasing-signal configuration when the relay must trip as pressure rises to the set point.
- Select a decreasing-signal configuration when the relay must trip as pressure falls to the set point.
- Select the high-signal configuration for monitored signal pressures above 50 psig.
- Select the low-signal configuration for monitored signal pressures below 50 psig.
- Select the standard reset button for typical installations.
- Select the long reset button when additional reach or panel accessibility is required.
- Use the remote pneumatic trip port when the relay must also be tripped from a separate location or control device.
- Confirm that system pressure does not exceed the 100 psig maximum pressure rating.
- Verify that the lock-up and vent outputs are connected to the correct downstream functions.
For additional guidance:
Applications
The Mite 70 is used in pneumatic systems that require immediate switching, pressure lock-up, venting, alarm activation, or safety shutdown based on a monitored pressure signal.
- Emergency safety-valve actuation
- High-pressure and low-pressure alarms
- Pneumatic shutdown systems
- Valve lock-up during abnormal process conditions
- Diaphragm motor-valve actuation
- Pneumatic cylinder control
- Remote pneumatic trip systems
- Oil and gas process controls
- Petroleum processing systems
- Chemical processing equipment
- Gas-field safety systems
- Pharmaceutical process controls
- Fail-safe pneumatic logic
- Critical process interlocks
Explore more applications:
Models & Configurations
Base Model
- Mite 70 = Snap-acting pneumatic control relay with manual reset, lock-up output, vent output, and remote pneumatic trip
Reset Button Configurations
- Standard Reset Button = Normal reset-stem length
- Long Reset Button = Extended reset stem for panel or recessed installations
Signal Configurations
- High Signal = For signal pressures above 50 psig
- Low Signal = For signal pressures below 50 psig
Trip Direction
- Increasing Signal = Trips when the monitored pressure rises to the selected set point
- Decreasing Signal = Trips when the monitored pressure falls to the selected set point
Use the ordering diagram in the current Mite Series specification sheet or contact ControlAir to confirm the complete ordering code for the required reset-button, signal-range, and trip-direction configuration.
Technical Resources
- Product Data Sheet
- Installation Instructions
- Product Configurator
- 3D CAD Models
- Engineering Support Resources
FAQs
What does the Mite 70 air relay do?
The Mite 70 monitors a pneumatic signal and switches when the selected trip point is reached. It locks pressure in one output line and vents a second output to atmosphere.
Can the Mite 70 trip on either rising or falling pressure?
Yes. It can be configured to trip on either an increasing or decreasing control signal.
What is the adjustable trip range?
The trip point can be adjusted from 1 to 100 psig.
What happens after the relay trips?
The Mite 70 remains in the tripped position until the control signal is restored and the manual reset button is pressed.
Can the relay be tripped remotely?
Yes. A separate pneumatic connection allows the Mite 70 to be tripped on demand from a remote signal.
What is the maximum pressure rating?
The maximum pressure rating is 100 psig (7 bar).
What port size does the Mite 70 use?
The relay is tapped for 1/4″ NPT connections with 1/8″ internal ports.
What is the operating temperature range?
The operating temperature range is -40°F to 180°F (-40°C to 82°C).
Does the Mite 70 require electrical power?
No. The Mite 70 is a passive, fully pneumatic relay.
What are common Mite 70 applications?
Common uses include emergency safety-valve actuation, pressure alarms, valve lock-up, pneumatic shutdown systems, actuator control, and process interlocks.
What is the difference between the Mite 70 and Mite 73?
The Mite 70 uses a manual reset and monitors a primary control signal. The Mite 73 can accept up to four inputs and can be reset pneumatically for fully automated control.
