HGD-2000 H₂ Hydrogen Detector and Sensor

OSHA Regulations (Standards – 29 CFR), National Electrical Code (National Fire Protection Association Standard NFPA 70), and associated directives, interpretations and compliance letters apply. For the latest information, see the web sites of OSHA (osha.gov) and NFPA (nfpa.org). Other regulations, state and local, may also apply.

To the best of our knowledge at the time of this posting, existing regulations require that:

• Provisions be made for sufficient diffusion and ventilation of gases from storage batteries to prevent the accumulation of explosive mixtures.
• Adequate ventilation means providing natural or mechanical dilution sufficient to limit the accumulation of hydrogen gas in air at the charging site to levels below the lower explosive limit of 4.1%.
• A typical exhaust fan can meet this requirement if it is used in such manner that the concentration of hydrogen gas in the fan’s ambient air never exceeds the lower explosive limit.
• What can cause a hydrogen gas explosion?
  Hydrogen gas, 4.1% or more mixed with air, can be ignited by a flame, spark, or static electricity.

Hydrogen gas, 4.1% or more mixed with air, can be ignited by a flame, spark, or static
electricity.

Not if you make tight wire connections to the detector. The only moving parts are in the internal relays, and the relays are hermetically sealed.

Hydrogen is a colorless, odorless gas. Human senses cannot detect it.

The odor in a battery room often is caused by a small amount of sulfuric acid vapor
escaping into the air during finish charge. It is not caused by hydrogen, which is odorless.

When lead acid batteries, on charge, reach approximately 2.38 volts per cell ( 80 % of
their full charge capacity ), they begin to gas. At that point, electrical energy in excess of
what is needed for the chemical reaction, decomposes the water of the electrolyte into
oxygen at the positive plates and hydrogen at the negative plates. Even after the
charger turns off, the cells continue to produce oxygen and hydrogen until the reaction in
the battery stabilizes.

Fully charged, lead acid batteries on float charge continually emit oxygen and hydrogen,
although at a lower rate than batteries being recharged.

The amount of hydrogen gas emitted during gassing depends upon the:
a. Charger output current.
b. Number of cells.
c. Condition of the battery.

Hydrogen exits flooded batteries through the vent plugs. The concentration at the vent
plugs is very explosive. As it exits, it dissipates in the air and, being the lightest of all
gasses, rises. It can accumulate again in explosive concentrations in the highest, draft-
free areas of the room. The main purpose of the hydrogen detector is to prevent this.

VRLA (valve regulated lead acid) sealed batteries use a recombination technique to
prevent water loss in the form of oxygen and hydrogen gas. They often require special
chargers with specific charge profiles for the brand and type of battery.

Although VRLA batteries normally do not emit gases, they can do so under certain
circumstances. They have pressure relief valves to control their internal pressure. If the
pressure builds too high due to high ambient temperature, overcharge, mechanical failure
or other causes, they can emit hydrogen gas in explosive concentrations. The potential
danger is greatest with stationary VRLA batteries kept in small enclosures with limited
ventilation.

No. The sensor requires an oxygen environment.

The sensor detects several other combustible gases in addition to hydrogen — ethanol, isobutane, methane, propane. Its sensitivity to these other gasses, however, is much lower than its sensitivity to hydrogen. This should not noticeably affect its operation.

The detector operating temperature is 14 to 104 degrees F, ( -10 to 40 degrees C).

When power is first applied, or after a power interruption, approximately 10 minutes will elapse before the detector starts to function. This delay is to prevent false activation. After this delay, response time to hydrogen for the first (1%) relay is about 4 seconds; response time for the second (2%) relay and/or alarm is 3 seconds later (total: about 7 seconds).

The detector has a built-in 80 db warning alarm that activates at a 2% concentration of hydrogen.

Install the detector at the highest, draft-free location in the battery compartment or room where hydrogen gas might accumulate.

The detector is designed to attach directly to a wall or ceiling, or to a conduit box, using four screws. You will need to run power and relay wires to the detector, plus a modular cable to the optional remote, if used.

Normal power is 115 volts 50/60 Hz AC. If specified at time of order, the detector can be customized for 220 volts 50/60 Hz AC, or for 24, 36 or 48 volts DC.

The detector consumes 80 ma, 170 ma if the buzzer is sounding.

The internal relay dry-contacts are rated at 10 amps / 250 vac, sufficient for most 1/3 HP fans. For higher current requirements, add an external relay.

Similar to smoke detectors, hydrogen detectors sense hydrogen only at the sensor, not at a distance. How many detectors you need depends upon where hydrogen might accumulate near your ceiling. Factors affecting this are: a. Room size. b. Type of ceiling — flat, pitched, compartmented, etc. c. Natural air flow patterns. If unsure, add one or more detectors to be safe.

No. The detector can operate only one sensor.

Normally, no. The sensor is mounted on a small board inside the detector. For special OEM requirements, some modifications can be made. Consult Eagle Eye.

Each detector has a test button. Push and hold the test button for ten seconds. The LED’s will light in sequence, the relay(s) will close to operate whatever is connected, and the warning buzzer will sound. This test can also be run from the optional remote, if used. This procedure will test the detector’s electronics, but not the sensor itself. There is no way accurately to test the sensor in the field. If you have hydrogen in a tank, you can fill a balloon with hydrogen and release it at the sensor to see the reaction. Do not use hydrogen sulfide – it can damage the sensor. For a more accurate test, you can purchase test gas from a gas supplier and flood the sensor with it, but these concentrations are very small and may not give a correct result. Fortunately, when the sensor fails, often due to contamination, it normally becomes more sensitive, falsely activating the relay and/or alarm.

The remote box connects to the detector box via a standard style 6-connector, 6-contact telephone-type modular cable.

Normal sensor life is over 5 years. For safety sake we suggest you replace it every 5 years.

To replace the sensor, order a new sensor board from your dealer or Eagle Eye. Remove the cover of the detector. Pull out the old sensor board and insert the new board. Replace the cover. Run the push-to-test-button procedure. That’s all there is to it.

Hydrogen gas detectors are warranted to be free of defects in workmanship and material for a period of 12 months from the date of purchase.

You can buy a detector directly from Eagle Eye Power Solutions, LLC.

You should consult your electrician or an engineer for the proper wire gauge for your application. You will want a wire gauge that is sufficient for carrying the appropriate load from your circuit breaker which may vary in size based on 120/220 VAC and your specific application.