Gastec H-3A Oxygen Sensor

Description

The H-3A operates on the galvanic cell principle, essentially functioning as a small atmospheric battery. Oxygen diffuses through the sensor’s membrane and is reduced at the cathode, while a specialized anode is oxidized. This chemical reaction generates an electrical voltage directly proportional to the concentration of oxygen in the surrounding air.

Because it is a galvanic cell, it requires no external power to generate its signal and has no warm-up time. Its dimensions ( $\phi$ 20 x 22 mm) are tailored to fit alongside $CO$ and $LEL$ sensors within the compact internal manifold of the GOMHC-3A.

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

Galvanic Cell Technology: Provides an immediate, self-powered response as soon as the monitor is turned on.
Miniaturized Design: At just 15g, it minimizes the overall weight of the portable unit, supporting all-day comfort for the user.
High Stability: Engineered to resist baseline drift caused by changes in atmospheric pressure and temperature during field use.
Linear Output: Delivers a consistent signal across the 0–25% range, ensuring the digital readout on the GOMHC-3A remains accurate.
Instant Readiness: Requires no polarization or lengthy warm-up period; it is ready for safety checks immediately upon startup.

Specifications

Feature	Specification
Model Number	H-3A
Detection Principle	Galvanic Cell
Compatible Device	GOMHC-3A
Dimensions	$phi$ 20 x 22 mm
Weight	15g
Target Gas	Oxygen ( $O_2$ )
Standard Range	0.0 – 25.0%

Applications

Multi-Sensor Array Integration: The H-3A is applied by seating it into the dedicated oxygen sensor port of the GOMHC-3A multi-gas monitor.

Installation: Open the monitor’s sensor compartment and firmly press the sensor into the 2-pin or 3-pin socket on the mainboard. Ensure the sensing face aligns with the diffusion inlet.
Immediate Start-up: While the sensor works instantly, allow the unit to sit in fresh air for 3 to 5 minutes after installation to reach thermal equilibrium with the environment.
21% Span Calibration: Perform a “Fresh Air Calibration.” In an environment with normal oxygen levels, adjust the monitor to read 20.9%.
Maintenance Check: If the monitor triggers a “Low Oxygen” alarm in fresh air or cannot reach 20.9% during calibration, the internal chemical capacity of the H-3A is exhausted and it must be replaced.