Gastec HS-7A Hydrogen Sulphide Detector

Description

The HS-7A utilizes an electrochemical sensor to detect $H_2S$ . When the internal pump draws air into the device, the gas reacts with the sensor’s electrolyte, creating an electrical current that the device converts into a digital ppm (parts per million) reading.

This model is a “non-dispersive” detector, meaning it is specifically calibrated for Hydrogen Sulphide and ignores common background gases like Methane or Carbon Monoxide, which are often found in the same environments. Its primary advantage over passive “clip-on” monitors is the built-in suction pump, which allows a technician to test an atmosphere from a distance using a sampling hose before entering a hazardous zone.

Brand

Gastec

Although, technology is always evolving, one demand on our products never changes: the demand for customer safety. Whenever we contribute to customer safety, we are presented with an opportunity to develop further.

GASTEC holds this corporate creed of safety and development in high esteem, as it strives to grow while always putting customer safety first.

Features

Built-in Diaphragm Pump: Allows for remote sampling (up to 30 meters with optional hose), essential for pre-entry safety checks in underground vaults.
Direct Digital Readout: Features a large, backlit LCD that shows the current concentration in real-time, eliminating the guesswork of color-change tubes.
Dual Alarm System: Includes a high-decibel audible buzzer ( $>85$ dB) and bright red LEDs that trigger at the standard OSHA/ACGIH STEL and TWA limits.
Peak Hold Function: Records the highest concentration detected during a session, which is vital for identifying “slugs” of gas that move through a sewer line.
Rugged Construction: Encased in a shock-resistant housing designed for the “dirty” conditions of wastewater and industrial maintenance.
Simple Calibration: Features accessible “Span” and “Zero” adjustment potentiometers (or digital menu) for field calibration with a standard test gas cylinder.

Specifications

Feature	Specification
Gas Detected	Hydrogen Sulphide ( $H_2S$ )
Detection Range	0 – 30.0 ppm (Standard) / up to 100 ppm
Resolution	0.1 ppm
Response Time ( $T_{90}$ )	< 30 Seconds
Sampling Rate	Approx. 0.5 L/min
Operating Temp	-10°C to +40°C
Power	AA Alkaline batteries or Rechargeable Ni-Cd

Applications

Sewer & Manhole Maintenance: Checking for “Sewer Gas” accumulation which can be lethal even at low concentrations.
Petrochemical Refineries: Spot-checking for leaks around “sour gas” processing equipment and storage tanks.
Pulp & Paper Mills: Monitoring emissions near black liquor tanks and recovery boilers.
Tunneling & Mining: Ensuring safe air quality in deep excavations where $H_2S$ can seep from geological formations.
Tannery & Food Processing: Monitoring decomposition gases in waste treatment areas.