LPT-A-VLT Ammonia Vent Line Transmitter

    Key Features

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    LCD display (with user selectable function)
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    1 dry contact relay, 30 volt 2 amp maximum
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    Internal audible alarm
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    Linear 4 - 20 mA or 0 - 10 volt output signal
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    3-wire VDC or 4-wire VAC power
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    24 volt DC or AC power (nominal)
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    Standard water / dust tight, corrosion resistant enclosure (drip proof) with splash guard; pending IP54 rating.
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    Thermal resetting fuses
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    RoHS compliant circuit board
The LPT-A-VLT Ammonia Vent Line Transmitter is designed for continuous monitoring of ammonia levels in the vent line of refrigeration systems.  More specifically, it is designed for the detection of equipment failure in ammonia plant vent stack applications. Using the 3/4” cast steel coupler, it can be mounted indoors on the ammonia vent relief stack above the pressure relief valve or mounted outside on the relief header above the roofline. It can be configured to alarm at user specified concentration levels and send an analog signal to the controller or PLC to activate the emergency ventilation system or shut down the equipment depending on the level of alarm.
It offers 3-wire VDC or 4-wire VAC power, jumper selectable 4 - 20 mA or 0 - 10 VDC analog output, a standard dry contact relay (2 amps @ 30 volts SPDT), automatic thermal resetting fuse, temperature compensation, back lit LCD display and audible alarm, all in a RoHS compliant package. 
Comes standard with a water / dust tight, corrosion resistant ABS / polycarbonate enclosure with a hinged, secured door. Calibration and other maintenance procedures are simple and easily performed in the field.
NOTE: This device is not designed to monitor ammonia in applications requiring human health safety levels detection.


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    Refrigeration Plants
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    Ice Arenas
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    Cold Storage or Freezer Rooms
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    ... and many more

Gas Types

Ammonia (NH3) 0 - 3.00% volume range (catalytic) Tolerant to 15% volume. NOTE: Ammonia is flammable between 15% (LEL) and 28% (UEL) volume in air.



Enclosure: ABS / Polycarbonate, IP54 rated, copper coated interior to reduce RF interference
Weight: 825 g (29 oz)

Transmitter only: 5.0” x 5.0” x 2.4” (127 mm x 127 mm x 60.96 mm)

Including steel connection:  5.0” x 5.0” x 6.275” (127 mm x 127 mm x 159.4 mm)


Power Requirement: 3-wire mode: 16 – 30 VDC, 3 W, Class 2
4-wire mode: 12 – 27 VAC, 50-60 Hz, 3 VA, Class 2
Wiring: VDC (or ground referenced AC) three conductor shielded 18 awg stranded within conduit
VAC four conductor shielded 18 awg stranded within conduit
Fuses: Automatic resetting thermal

Input / Output


Linear 4 - 20 mA
Maximum 216 Ω load (wiring plus termination resistor) @ 12 VDC
Maximum 316 Ω load (wiring plus termination resistor) @ 12 VAC
Voltage 0 - 10 volt
Minimum 1k ohm load

1 dry SPDT contact, 2 amps @ 30 V Relay

User Interface

Display: Graphic LCD
Text prompting for calibration operation and fault indications.
Installer configurable to suppress all other displays.


Operating Temperature: -20°C to 40°C (-4°F to 104°F)

NOTE: Low temperature option available to -40°C (-40°F)
Humidity: 0 - 80% RH non-condensing



Conforms to: CSA-C22.2 No. 205-M1983 (R2009)
                        UL508 (Edition 17):2007
Conforms to: EMC Directive 2004/108/EC
                        EN 50270:2006, Type 1, EN61010
Conforms to:  FCC. This device complies with part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) This device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation.

More Brochures

Product Specifications

Application Brochures



Sensor Specification

Engineering Specification Samples


Operation Manual

Part Numbers

Description Code
Catalytic ammonia (NH3) sensor (0 – 3.0% volume range), LCD display, 4 - 20 mA or 0 - 10 VDC output, three-wire VDC or four-wire VAC power, 2 A @ 30 V SPDT contact relay, audible alarm, water / dust tight enclosure rated IP54 with splash guard; power coated cast steel sensor assembly and coupler for mounting on ammonia vent relief stack  LPT-A-VLT-NH3-S

Remote Devices

Description Code
Remote Horn/Strobe Combo, rated 100 dB @ 3 m (10 ft)  RSH-24VDC
Remote Audible Alarm, rated 90 dB @ 30 cm (0.98 ft)  RAA-90
Remote Audible Alarm, water tight audible, rated 85 dB @ 60.96 cm (2 ft)  RAA-90-W

Metal Protective Guard

» 16 gauge, clear anodized metal protective guard
» Larger size for controllers & self-contained systems
» Smaller size for analog & digital transmitters

Calibration Kit

» Commonly used tools required for calibration in one convenient toolbox

RSH-24VDC Remote Strobe & Horn Combo (with Enclosure)

» Two alarm features combined into one device
» Light weight, weather and corrosion resistant
» Independent settings for horn, strobe or horn and strobe together
» Surface mount and 1/2” NPT conduit mount
» ABS / Polycarbonate water / dust tight enclosure

Remote Audible Alarm

» Loud remote audible alarm
» Easy installation
» 2-wire VDC
» Standard corrosion resistant enclosure
» Water tight option available for wet or wash down environments

Magnetic Wand

» Used for non-intrusive calibration of the LPT-A and SCC
» Use to access menu options and initiate non-intrusive calibration for the LPT-M, LPT-P, LPT-B, DCC and CXT

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