Australian safety equipment specialist OTB says common myths about two-way communications rescue equipment could have tragic consequences in confined space accidents, which are one of industry's biggest killers.
OTB managing director David Reed says too few companies appreciate the differences between simplex and duplex two-way communications, only the latter of which permits simultaneous two-way communication to save precious seconds in hazardous situations.
With duplex systems, users are hard-wire connected to their attendant/rescue base so they can exchange information about rapidly evolving emergencies in much the same way people talk face to face.
With radio simplex, only one person can talk at one time, usually terminating with "over" or "over and out" before the channel is clear for the person to whom they are speaking.
Such comparatively stilted conversation on simplex systems can cause delay and confusion, says Mr Reed, whose Con-Space equipment is used by some of the most safety-conscious organisations in Australia, including military and civil aviation.
"You only enter a confined space when all other options have been ruled out or a rescue attempt is necessary rescue," says Mr Reed.
"Confined space rescues can be incredibly dangerous - it is a tragic irony that more would-be rescuers die than those being rescued, by a factor of 1.7 to 1.
"Workers and rescuers going into confined spaces like tanks, tunnels, bins and pipelines are often faced with limited/restricted entry, difficulties with communication, dangerous atmospheric conditions, lack of oxygen and the presence of toxic or flammable gases. It is a lethal combination that should be avoided whenever possible," he says.
Once a decision has been made that entry is the only way to achieve the purpose required, then, along with the vital precaution of testing the atmosphere, a crucial safety question is: 'how can we stay in touch with the entrant every second' - "and I mean, every second, and in a duplex form of communication, ie, with communication equipment that permits simultaneous two-way communication.
“This is where the common misunderstanding arises in the distinction between this duplex and the more common simplex communications equipment,” says Mr Reed.
"Simplex communications are two-way in the sense that communication is possible back-and-forth between the person inside (entrant) and the person outside (attendant), but only with one person talking at a time.
"That's why professional rescuers using simplex radios keep messages as short as possible, leaving the channel open for any vital communications. But a safer, more practical method for confined space entries is a full duplex system, through which the person inside and person outside can talk at the same time, so there are absolutely no delays in vital communications or alarms. After all, tragic situations can happen in seconds or fractions of seconds."
The Australian Standard recommends the use of full duplex communications when there is no Line of Sight between entrant and attendant, or where other forms of communications are ineffective. This equipment, plus permit-controlled entries when applied, should create the safest conditions. But there are always the unpredictable situations that can occur and, of course, interpretations of rules that could be described as grey areas, says Mr Reed.
"One such grey area arises from misinterpretation of the Line of Sight rule. If the attendant has to bend down or stretch up to see the entrant you can almost guarantee they won't do it often enough. Or, if the distance between makes hand signals unclear, then the Line of Sight rule is inappropriate. In these situations, there is no doubt that full duplex communications offer the safest and most reliable form of communications.
"But an issue is created in many potential users' minds by the fact that generally full duplex systems are hardwired systems - and here is where the blinkers go on with some potential users.
"But, in truth, there are so many advantages to using a duplex system that they overwhelm such blinkered views. All people need to look closely at the whole picture, taking into account the quicker entry possible, being able to hear the entrant at all times, clear static-free communications and completely hands-free operation with no Push To Talk (PTT) buttons to push. And duplex equipment can be worn with respirators, full SCBA and chemical suits, plus back up alarms. This simplicity reduces entrant and attendant stress (attendants stress more than entrants).
"There is no interference with duplex systems, which are secure private systems with 200/400 hr battery life. They are not reliant on radio signal penetration, are totally water proof, cannot be dropped and are less fragile than radios. Also you can use the hardwire to backtrack to the entry in incident-related poor visibility conditions.
"These are enormous benefits that often go unsung. They have far-reaching productivity and safety gains in routine jobs as well as rescues. They should be considered an investment in efficiency and safety equipment, rather than another cost," said Mr Reed.
Con-Space Confined Space communications systems from OTB include:
* CSI1100 Mini module, 1 on 1 up to 1 on 3 system, CSI2100 1 on 3 up to 1 on 7 system.
* CSI - Talk box System for monitoring and for low noise entry.
* Inspection CSI - Hi noise system for work in high noise areas.
* SR65I Radio accessory, for use when radio can be used successfully and especially suited to times when respirators have to be worn.