TD7800 Electro Pneumatic Converter
The TD7800 is an electro pneumatic converter for use with pneumatic control valves.
What This Model Does
The TD7800 is an electro pneumatic converter for use with pneumatic control valves. It takes a DC 4 to 20 mA signal from a controller or DCS and converts it into a proportional pneumatic output pressure. It is a form fit and function replacement for the Fairchild T7800 series transducer already installed on many control valve systems. The unit operates with a piezoelectric actuator and internal electronic feedback to maintain stable output pressure under vibration or changing orientation.
| Model | TD7800 |
|---|---|
| Type | Electro pneumatic converter (I/P transducer) |
| Output pressure | Proportional to input signal |
| Reversibility | Field reversible for inverse output |
| Enclosure rating | NEMA 4X, IP65 |
| Environmental use | Indoor and outdoor |
| Certification | Canadian Registration Numbers (CRN) for all provinces and territories |
| Actuator type | Solid state controlled piezoelectric actuator |
| Feedback | Internal electronic feedback |
| Mounting | Multiple configurations available |
| Damping | Adjustable for tuning response |
| Split range | Supported |
Why Buyers Specify This Model
- Converts a 4 to 20 mA electrical signal directly to a proportional pneumatic output, eliminating the need for a separate I/P transducer
- Internal electronic feedback maintains output pressure stability despite vibration or changes in mounting position
- Field reversible option allows output to be inversely proportional to input signal, useful for split range or reverse acting control
- RFI/EMI protection reduces signal interference from nearby electrical equipment
- Damping adjustment allows tuning for fast or slow response to input changes
- Split range operation lets one controller output manage two or more valve functions
- Compact size fits in tight spaces where larger transducers cannot be installed
- NEMA 4X and IP65 rated enclosure allows use in both indoor and outdoor environments
Problems It Solves
- Original brand transducer is discontinued or on long lead time
- Transducer fails due to electromagnetic interference in a noisy electrical environment
- Output pressure drifts under vibration or when mounted in non-standard positions
- Need to reverse the actuator action without changing the controller signal
- Existing transducer is too large for the available mounting space
- Control system requires split range operation but the current transducer does not support it
Application Scenarios
- Replacing a failed Fairchild T7800 transducer on a control valve in a chemical plant with a long lead time
- Installing a transducer in a new skid-mounted unit where space is limited
- Using split range control to sequence a heating valve and a cooling valve from a single controller output
- Running a control loop in a high vibration area such as a pump station or compressor house
- Requiring a transducer that can operate reliably outdoors in a refinery or offshore platform
- Need for a field reversible transducer to reverse the actuator action without changing the controller output
Who It Is For
- Plant instrument technicians replacing worn or failed transducers on control valves
- EPC contractors procuring transducers in bulk for plant projects
- Valve and actuator OEMs who need branded transducers under their own name
- Distributors stocking Fairchild T7800 replacements for local process plants
- Maintenance teams needing a transducer with field reversible capability for split range service
Technical Features
- Converts DC 4 to 20 mA input to proportional pneumatic output pressure
- Piezoelectric ceramic actuator functions as a flapper in the nozzle system
- Internal electronic feedback maintains output stability
- Field reversible mode for inverse output response to input signal
- RFI/EMI protection for reliable operation in electrically noisy areas
- Damping adjustment for tuning response speed
- Split range operation supported
- Compact design for installation in restricted spaces
- NEMA 4X and IP65 rated enclosure for indoor and outdoor use
- Multiple mounting configurations for flexible installation
Materials and Construction
- Die-cast aluminium housing with corrosion-resistant finish
- Stainless steel mounting hardware and internal components
- Piezoelectric ceramic actuator and flapper assembly
- Full material and finish breakdown is available in the datasheet PDF
Dimensions and Connection Detail
Reference image published with this model on the original catalogue. Confirm critical dimensions against the datasheet before machining a bracket.
Manufacturing and Quality Control
Every unit is calibrated and stroke tested before it is packed. We can film or photograph your units in the sample room or warehouse before they ship.
Manufacturing Steps
Housing die-casting and machining
Assembly of piezoelectric actuator and nozzle flapper system
Integration of internal electronic feedback circuitry
Calibration on an air bench across the 4 to 20 mA input range
Damping adjustment and split range testing
Enclosure sealing and IP65/NEMA 4X compliance check
Final inspection and packaging in standard or custom cartons
Quality Control
- Every unit is tested for output pressure accuracy across the 4 to 20 mA range
- RFI/EMI performance verified under simulated industrial conditions
- Field reversible function tested and confirmed
- Enclosure sealed and rated for IP65/NEMA 4X before packing
- Photos or video of actual units can be provided on request before shipment
- Faulty units within the 18 month warranty are replaced on photo or video evidence, not repaired
Customisation Options
- Customer logo and nameplate marking
- Housing painted in customer colour (black, blue, yellow, or custom)
- Custom mounting brackets or configurations developed to customer drawings
- Custom packaging and carton design
- Supplied with or without limit switch box or position transmitter module
How It Compares With the Alternatives
| TD6000 transducer | The TD7800 has field reversible output and internal electronic feedback; the TD6000 uses mechanical feedback and does not support field reversal |
|---|---|
| Pneumatic positioner | A positioner controls stem position; the TD7800 only converts signal to pressure and does not provide feedback to the valve stem |
| I/P transducer with mechanical flapper | The TD7800 uses a solid state piezoelectric actuator and electronic feedback, which is more stable under vibration than a mechanical flapper system |
| Digital intelligent transducer | The TD7800 is a lower cost analog solution; digital units add HART communication and diagnostics, which are not needed for basic signal conversion |
Fitting and Setting Up This Model
General field procedure. Always follow the datasheet for the exact calibration sequence and any hazardous area requirements.
Mount the transducer using the preferred configuration for your space and access needs
Connect clean, dry instrument air to the supply port and the control valve to the output port
Wire the DC 4 to 20 mA signal to the input terminals, observing correct polarity
Set the damping adjustment to a mid-range position for initial tuning
Test the output pressure at 4 mA and 20 mA; adjust zero and span if needed
For split range, calibrate the zero and span to the assigned half of the signal range
Enable field reversibility if the output needs to be inverse to the input signal
Check air filter regulator regularly; dirty air can cause drift or clogging
TD7800 Electro Pneumatic Converter FAQ
Will this fit the bracket already on my actuator?
If the actuator currently uses a Fairchild T7800 transducer, yes. Send a photo of the existing mounting bracket and connection ports via WhatsApp and we will confirm before you order.
What is the lead time?
Regular quantities normally ship in 2 to 3 days from stock. Large project quantities take 7 to 10 days.
Can I get it in our own colour with our logo?
Yes. The housing is painted to your colour and the nameplate carries your logo. Black, blue, and yellow are standard; other colours are painted to order.
What is the difference between TD7800 and TD6000?
The TD7800 has field reversible output and internal electronic feedback; the TD6000 uses mechanical feedback and does not support field reversal.
What happens if a unit fails on site?
The warranty is 18 months. Send photos or a short video, and we ship a replacement unit rather than asking you to return it for repair. It normally travels with your next order, or on its own if the plant is down.
Can I see the actual units before they ship?
Yes. Ask on WhatsApp and we will photograph or film the units in the sample room or warehouse before packing.
Is it suitable for outdoor use?
Yes. The unit has a NEMA 4X and IP65 rated enclosure, so it can be used in outdoor environments, including wet or dusty areas.
Applications Cases and Guides
Related Products
Get A Price on This Model
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