Posted on 03 May 2010.
If you work in a strata warehouse with offices in the front and manufacturing and / or service work taking place in the rear, you may be exposing yourself to harmful gases and vapours without realizing it.
Think about it.
You spend 6 to 8 hours of your day at work and chances are you have minimal ventilation at best. Poor indoor air quality can cause symptoms such as Sick Building Syndrome and Building Related Illness.
Sick Building Syndrome is related to chemical, particulate or biological exposure that cannot be related to a specific cause but are alleviated when the occupant leaves the building. Individuals report symptoms such as headaches, nausea, fatigue and drowsiness, to eye, nose, and throat irritation.
Building-Related Illness is a specific illness with a known cause that is a result of exposure to an indoor agent. Examples are Legionnaire’s disease and Pontiac Fever.
Commercial gas detectors should be placed not only in the rear of the strata unit where the work is taking place but in the front offices for the protection of administration staff as well. Buying a low cost residential carbon monoxide (CO) detector is simply not sufficient in a work place as seen in the comparison table below.
Residential Gas Detectors
- Low Cost
- Easily found in local hardware stores
- Alarm on a timed basis
- Cannot activate ventilation equipment, phone dialer or any other alarm or notification device
- Only calibrated before it leaves manufacturing plant.
- Exposure limits for 8-hour time weighted average (TWA) and for 15-minute short term exposure limit (STEL) time periods
Commercial Gas Detectors
- More expensive than residential gas detectors
- Must be purchased through an authorized distributor/contractor
- Alarm condition when the 15-minute average limit has been reached or surpassed
- Can be set up to automatically activate ventilation equipment, a phone dialer or virtually any other alarm or notification device using the on-board dry contact relays
- Workplace must meet local (provincial, state, OSHA-USA) health and safety exposure standards for toxic gas exposure
- Professionally calibrated every month for toxic environments and 6 months to a year for non-toxic environments.
- Provide a warning when the 8-hour average limit is reached or surpassed
Worker safety is first and foremost. Depending on what kind of work is being carried on in your place of business, some things need to be considered before purchasing a gas detector: the types of gas(es) to detect, sensor placement, and migration of gases.
You may need or desire to have gas detectors for other gases such as combustibles (flammables) which would include natural gas, propane, solvent vapours, paint vapours, etc.
Sensor placement is important for early detection and consideration must be given to the target gas. For example, natural gas is lighter than air while propane and all solvents are heavier than air. Therefore, it is recommended that natural gas sensors should be placed near the ceiling and propane sensors should be placed 6” above the floor. If sensors are to be installed in areas that could or will be considered “wash down” areas, it is imperative that a water tight enclosure be selected and a splash guard for protection of the sensor and internal electronic circuit. It is also important to ensure that the installer takes the proper steps to seal the conduit or wiring leading into the transmitter to prevent liquid incursion by using the proper conduit seals or water tight cable clamps.
The migration of toxic or combustible gases between neighboring strata units depends on the type of work they are carrying on. For example, CO is only slightly lighter than air and can migrate very easily throughout a building.
Once gas detectors are installed, they eventually need to be serviced for not only best performance but to ensure they respond well and quickly to the target gas and provide early detection of unsafe gas build up. Most local agencies responsible for health and safety regulations require that work place gas detectors be “bump” tested for safety. This means exposing the sensor(s) to a known concentration of the target gas and confirming they respond to it. If this is an enforced requirement, it may be too costly to purchase the equipment required to achieve this goal. In cases like this, your local gas detection supplier or service company may provide this service. When considering bump testing of sensors, it is important to discuss this with experts in the gas detection field. Some sensors are consumable and bump testing them with high concentrations of target gas to get them into alarm condition can shorten then life span of a costly sensor element.
Always discuss your application with your local gas detection equipment manufacturer / supplier to ensure you get the proper product for your application and to ensure you are aware of the maintenance / service costs, sensor life spans, cost of sensor element replacement, etc. then budget for these things.
Written by: Frank Britton, CETCI’s General Manager