Flameproof Duct Humidity Temperature Transmitter (AI-RHTx-D-FLP)
Temperature and humidity measured inside the duct, in places where an ordinary sensor cannot go. A flameproof transmitter with a stainless steel probe, a CIMFR certified housing, and separate outputs for each reading.
Duct air readings from where only flameproof equipment may go.
The AI-RHTx-D-FLP measures the temperature and relative humidity of the air moving through a duct, and it is built for ducts that pass through or serve hazardous areas. A stainless steel probe goes into the airstream, and the electronics sit in a flameproof aluminium LM-6 housing, certified by CIMFR, Dhanbad, for Gas Group Areas I, II, IIA, and IIB.
Each reading has its own output, so a controller, a BMS, or a cleanroom scanner can read temperature and humidity separately. You choose the output type when you order: two 0 to 10 VDC outputs, two 4 to 20 mA outputs, or RS-485 Modbus. A local display is available as an option.
Sense, convert, send
The probe is inserted into the duct through the duct clamp that comes with the transmitter. A CMOS sensing element measures the temperature and the relative humidity of the moving air. The transmitter converts the two readings to output signals, with a fixed resolution of 0.1 for both. The signals leave the transmitter through its cable gland and go to the system that uses them.
The same readings, on the spot
With the optional display fitted, the same readings also appear on a two line LED display at the transmitter.
An illustration of the two line, four digit LED display. Values shown are examples only.
Built for ducts in hazardous areas
Flameproof Housing
Aluminium LM-6, certified by CIMFR, Dhanbad, for Gas Group Areas I, II, IIA, and IIB
Duct Probe in Stainless Steel
A 304 stainless steel pipe, 250 mm long as standard and 8 mm in outside diameter, with the probe length customizable
CMOS Sensing Element
For temperature and relative humidity
Three Output Options
Two 0 to 10 VDC outputs, two 4 to 20 mA outputs, or RS-485 Modbus
Separate Temperature and Humidity Signals
Each reading on its own channel in the analog versions
Accuracy
±0.3°C ±1 count for temperature, and ±1.8% RH for humidity from 10 to 95% RH
Optional LED Display
Two lines, four digits, seven segments, at an additional charge
Duct Clamp Included
For mounting the probe in the duct
Where the AI-RHTx-D-FLP is used
Pharmaceutical Manufacturing Areas with Flammable Solvents
Measures the temperature and humidity in HVAC ducts serving classified zones, so the air conditions can be verified where only flameproof equipment may be installed
Bulk Drug and API Facilities
Provides duct air readings in plants that handle solvents, so the supply air stays within the conditions the process needs
Chemical and Petrochemical Plants
Monitors ducts in areas with explosion risk, where an ordinary sensor would not be allowed
Industrial Hazardous Areas with HVAC
Gives air handling systems a temperature and humidity signal from inside the ductwork
Controlled Environments Needing Flameproof Equipment
Covers HVAC duct monitoring wherever the specified flameproof construction is required
Measure where the hazard is
A duct is not always outside a hazardous area. Ducts can run through classified zones, and the air in them can carry flammable vapors from the process. An ordinary transmitter with a plastic enclosure is not suited to that.
The AI-RHTx-D-FLP puts the electronics in a flameproof housing certified for the specified gas groups, so the sensor can be installed where the hazard is, instead of measuring far away and guessing.
A 250 mm stainless steel probe
The probe is a 304 stainless steel pipe, 250 mm long as standard and 8 mm in outside diameter, with an aluminium LM-6 housing. The probe length is also customizable. A duct clamp comes with the transmitter, and the cable enters through one 19 mm double compression gland. Plan the duct opening, the probe insertion depth, and the cable route before you install it.
Pick the output that matches your system
You specify the output type when you order. Pick the one that matches the input on the system that will read it. The analog versions connect to controllers that accept 4 to 20 mA or 0 to 10 VDC.
0 to 10 VDC
Two 4 wire outputs, one for temperature and one for humidity
4 to 20 mA
Two outputs, one for temperature and one for humidity
RS-485 Modbus
One digital output for a BMS, a PLC, or an HVAC automation system
A local display is available at an additional charge. It has two lines of four 7 segment red LED digits, so a technician at the duct can read the temperature and humidity without going to the BMS. It is useful for commissioning, troubleshooting, and spot checks.
Five checks before the probe goes in the duct
Check the area
Confirm that the gas group and the temperature class of the housing suit the hazardous area where it will be installed. The housing is certified for Gas Group Areas I, II, IIA, and IIB.
Check the wiring
Use cable glands and wiring practices that are approved for the area. The complete installation, not only the instrument, has to meet the applicable flameproof requirements.
Check the duct
Confirm the duct size, the space around the opening, and the insertion depth.
Check the output
Make sure the output you ordered matches the input of the system that will read it.
Check the power
The transmitter needs 24 VDC at 200 mA.
Technical specifications
Humidity: 0.0 to 100.0% RH typical
Option 2: 2 x 4 to 20 mA, one each for temperature and humidity
Option 3: RS-485 Modbus
Humidity: ±1.8% for 10 to 95% RH, ±2% for all other ranges
Check on a schedule
Check the probe, the cable gland, and the wiring on a regular schedule, and verify or calibrate the transmitter against a reference on the schedule your quality system sets. Ask our team about calibration and certificate options for your project.
Certified housing, your installation
The instrument housing of the AI-RHTx-D-FLP is certified by CIMFR, Dhanbad, for Gas Group Areas I, II, IIA, and IIB. That describes the housing, and it does not approve an installation, which depends on your hazardous area classification and on approved wiring and cable glands.
The transmitter assists your monitoring by providing a measurement signal for a BMS, PLC, or controller. It does not store records or raise alarms by itself, and it does not replace your commissioning and validation work. Ace Instruments manufactures under an ISO 9001:2015 certified quality management system.
Frequently asked questions
1. What is the AI-RHTx-D-FLP Duct Humidity and Temperature Transmitter?
The AI-RHTx-D-FLP is a flameproof duct mounted transmitter designed to measure temperature and relative humidity inside air ducts. It provides separate output signals for both parameters, allowing HVAC and environmental monitoring systems to monitor duct conditions continuously.
2. Why is it important to monitor temperature and humidity inside HVAC ducts?
Monitoring temperature and humidity inside ducts helps facility operators understand the condition of the air being circulated through a building. These measurements support HVAC system monitoring and help maintain the required environmental conditions in different areas.
3. Which parameters does the AI-RHTx-D-FLP measure?
The transmitter measures two parameters:
- Temperature in degrees Celsius (°C)
- Relative humidity in percentage (%RH)
4. What are the measurement ranges of the transmitter?
The standard measurement ranges are:
- Temperature: 0 to +50°C
- Relative humidity: 0 to 100% RH
5. What type of sensors are used in the AI-RHTx-D-FLP?
The transmitter uses a CMOS sensing element for both temperature and relative humidity measurement. These sensors are integrated into the duct mounted sensing assembly.
6. How accurate are the temperature and humidity measurements?
The specified measurement accuracy is:
- Temperature: ±0.3°C ±1 count over 0 to +50°C
- Relative humidity: ±1.8% RH between 10 and 95% RH, and ±2% RH for other ranges
7. What output signals are available?
The AI-RHTx-D-FLP offers three output configurations:
- Option 1: Two 0 to 10 VDC outputs, one each for temperature and humidity.
- Option 2: Two 4 to 20 mA outputs, one each for temperature and humidity.
- Option 3: RS-485 Modbus output.
8. Can temperature and humidity be monitored separately through the output signals?
Yes. The transmitter provides separate outputs for temperature and relative humidity when using the analog output configurations. This allows both measurements to be connected to compatible controllers or monitoring systems.
9. Can the AI-RHTx-D-FLP be integrated with a Building Management System (BMS)?
Yes. The transmitter offers an RS-485 Modbus output option for communication with compatible BMS, PLC, and HVAC automation systems. The analog output configurations can also be connected to compatible controllers that accept 4 to 20 mA or 0 to 10 VDC signals.
10. Does the transmitter have a built-in display?
A local display is available as an optional feature at additional cost. It consists of a two line, four digit, seven segment red LED display that allows users to view temperature and relative humidity readings at the installation location.
11. Why is a flameproof enclosure important for this transmitter?
The AI-RHTx-D-FLP is designed for applications requiring flameproof instrument construction. Its aluminium LM-6 instrument housing is certified by CIMFR, Dhanbad, for use in the specified gas group areas I, II, IIA, and IIB.
12. Where can the AI-RHTx-D-FLP be installed?
The transmitter is designed for installation in air ducts. It can be considered for HVAC duct monitoring applications in industrial and controlled environments where temperature and humidity measurements are required and the specified flameproof construction is needed.
13. How is the transmitter mounted inside an air duct?
The AI-RHTx-D-FLP uses a duct mounted arrangement with a duct clamp provided for installation. Its stainless steel sensing pipe is inserted into the duct so that temperature and humidity can be measured within the moving air.
14. What materials are used in the sensing assembly and enclosure?
The sensing assembly uses a stainless steel 304 duct pipe with an aluminium LM-6 housing. The main instrument housing is made of flameproof aluminium LM-6 construction certified for the specified gas group areas.
15. What power supply does the AI-RHTx-D-FLP require?
The transmitter operates on a 24 VDC power supply with a specified current requirement of 200 mA. The power connection should be made according to the supplied connection diagram.
16. What are the dimensions of the duct mounted sensing assembly?
The specified sensing assembly dimensions are:
- Length: 250 mm as standard, and the probe length can be customized
- Outside diameter: 8 mm
17. What should be considered before installing the AI-RHTx-D-FLP?
Before installation, check the duct dimensions, available mounting space, sensing pipe insertion depth, required output configuration, power supply, and cable entry arrangement. For hazardous area installations, ensure that the complete installation follows the applicable flameproof equipment and wiring requirements.
18. How can I select the right configuration or request a quotation for the AI-RHTx-D-FLP?
When requesting a quotation, specify the required temperature range, output configuration (0 to 10 VDC, 4 to 20 mA, or RS-485 Modbus), and whether you need the optional LED display. Also share your duct installation details and application environment so the technical team can help identify the suitable configuration.
19. How is the AI-RHTx-D-FLP different from the AI-RHTx-D?
Both measure temperature and humidity in a duct. The AI-RHTx-D-FLP has a flameproof aluminium LM-6 housing, certified by CIMFR, Dhanbad, for Gas Group Areas I, II, IIA, and IIB, so it can be used where flameproof equipment is required. The AI-RHTx-D is the standard version in an ABS enclosure for ducts that are not in a hazardous area.
20. How can I contact Ace Instruments about this transmitter?
For specifications, ranges, output options, or installation guidance, contact the Cleanroom Monitors team through the contact page. Please share your duct details and your hazardous area classification.
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