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The Greer series of detector products are industrial quality gas sensor transmitters. They provide a low cost and accurate way to detect ammonia, CFC refrigerants and a variety of other gases in accordance with ASHRAE and other industry standards. AS-400's are available in a number of configurations, allowing you to choose the correct model for your monitoring and alarm needs.

Each model provides all of the standard features listed above, including LINEAR 4-20ma output. There is even an LED which flashes in conjunction with the number of milliamps being output! A dry contact closure output is optional. The AS-400 series detectors are packaged in a non-metallic NEMA 4 enclosure with a LEXAN label and are designed to withstand the harsh abuses possible in an industrial environment. A heated version is specifically designed for reliable service in environments below -10°F.

AS-400's function as an ideal compliment to Greer Systems' control systems and together can provide you with an integrated monitoring solution. Suggested applications include ammonia and other refrigerant gas leak detection, battery charging room gas monitoring, parking garage gas monitoring and refrigeration vent line monitoring. When used with an Greer Systems' controller such as the model AP-100, high values can be stored for later reference.

Greer Systems can assist you in specifying the correct gas detector for your needs based on desired detection level and ambient conditions. In addition to phone and email contact, our website contains technical notes ready to assist you 24 hours a day. At Greer Systems we're committed to providing the best systems to meet your needs.


100+ Years Of Combined Refrigeration
Knowledge And Experience

Key Features

Solid State Sensor

Linear 4-20ma output proportional to gas concentration

Factory configured for specific gases

VeriCheck™ LED's show diagnostic information

NEMA 4 Enclosure

12-24 Volts AC/DC powered

Optional Heated Enclosure

Optional Contact Closure Output


AS-400-A: General Gases [future]

AS-400-C: Ammonia, 0-400 PPM [future]

AS-400-D: R22, R134a, & other CFC gases

AS-400-E: Ammonia, 0-1,000 PPM

AS-400-E-HE: Heated Detector for -10° to -40°F, internal LED's only

AS-400-F: Ammonia, 1,000-40,000 PPM

AS-400-H: Hydrogen, 0-10,000 PPM

AS-400-CO: Carbon Monoxide, 0-1,000 PPM

AS-400-VLF: Vent Line Ammonia Detector, 3/4" Stainless Steel Plug, 0-40,000 PPM

VeriCheck™ LED Operation

Sensor (Red):

OFF - Sensor is operating properly [normal state]

Flashing - Sensor not functioning [fault condition]

Microprocessor (Green):

On (Steady) - Transmitter and electronics operating properly [normal state]

Off - No power to unit

Flashing - Power is present but sensor is not operating properly

Range (Yellow):

ON (Steady) - Unit is at or above 20ma [fault condition]

OFF - at or below 4ma [fault condition]

Flashing - Number of flashes number of milliamps being output [normal state]


Sensor Element: Solid state metal oxide Sensor Life: 5 - 1 0 years CD Sensor Accuracy: +/- 5% (Contact Factory) Range: Depends on model

Temperature: -10°F - 125°F, -40°F - 125°F

Storage Temp: -4°F - 140°F

Response speed: 30 seconds to full response

Case: NEMA 4 non-metallic with gasketed cover

Case Size: 5" x 5" x 3" (7" X 7" X 3) *


VLF: 1 lb.

HE: 3 lb.

all others: <1 lb.

Wiring Access: Six (6) ½" knockouts

Output: Linear 4 - 20 milliamp **

Signal: Isolated/Non-isolated, jumper selectable

Max Loop Resistance: 500 ohms 12v 1,000 ohms at 24v

Power Required: 12 - 24v AC/DC

Power Consumption: .2 amp

Fuse: 1 amp AGC