Obsolete gas cylinder regulators

BOC Gases and ANU OHS Unit wishes to warn of a potential safety hazard associated with the use of obsolete gas cylinder regulators. The regulators of concern are BOC/CIG regulators -

• RA, part number T200.
• RB, part number TR1.
• RG, part numbers TR61, TR63, TR85, TR86, TR92 with 20000 kPa or 3000 psi gauges.
• RJ, part numbers 301178 (mini), TR358 (comet sprint).
• Monitor Oxygen Regulators, part numbers 30105 (hand tightening), 301055 (spanner tightening), 301152 (gaugeless).

These have the following safety hazards concerns -

• They are beyond the recommended life of a serviceable regulator. These regulators have been out of production for over 10 years and no suitable replacement parts are available.
• They are not suitable for regulating modern gas cylinders, which operate at cylinder pressures of 175 bar and above. The obsolete regulators have been superseded by regulators (eg the Comet 500 or 700 series) capable of regulating modern high cylinder pressures.
• Their use under certain conditions, can lead to a potentially dangerous situation where the regulators can fail resulting in sudden escape of gas, projection of broken parts, damage to equipment and/or an explosion.

It is recommended that the obsolete regulators be taken out of service as soon as possible.

Contact BOC Gases (131 262) for a recommended replacement.

For further information email: OHS Officer

Reference

BOC Gases - Safety Warning, Mr J Medforth, 17 October 1997

Electric shock from an aged electrophoresis powerpack

A laboratory worker was preparing to run an electrophoresis gel. She reached up to the electrophoresis powerpack on the shelf above the workbench to insert the power lead for the gel tank. The person experienced a severe electric shock and her hand was flung away from the powerpack. Her other hand may have been resting on a waterbath at the time.

The powerpack was found to have an intermittently malfunctioning voltage control and to be of an electronic design that made is intrinsically less safe than current models. The power pack had been purchased in 1989.

It is recommended that any electrophoresis powerpack that was purchased before 1990 be taken out of service, that remaining in-service powerpacks have isolated or "floating" terminals as the minimum safety requirement, and that all newly-purchased powerpacks have the following electrical safety features:

• An isolated powerpack. The powerpack is "floating", meaning the red and black terminals are NOT referenced to the case (earth),
• Electrical supply to the powerpack is protected with a Residual Current Device. The RCD will detect if either the red or black terminal is connected to earth by the electrophoresis apparatus and then turn off the electrical supply to the unit.
• Load detect system. This will not allow power to be supplied if there is no load on the output terminals.
• Reset on / Turn on. When the electric power is turned off and then on, all controls are automatically reset to zero.
• Standby mode. Powerpacks with a STANDBY mode are inherently safer to use.

It is important to recognise that electrophoresis has inherent potential dangers and, in addition to the design changes required above, it is recommended that the following administrative controls be put in place in laboratories where electrophoresis is being undertaken:

• Electrophoresis equipment must be set up in isolation from other earthed electrical items. No sinks, taps, waterbaths, refrigerators, incubators, etc. should be able to touched while operating electrophoresis equipment.
• The powerpack must be located at a height that is suitable for the operator. A unit that is too high means that the operator cannot insert or remove plugs cleanly and securely.
• The safest leads for electrophoresis are those which have a spring-sealed casing to shield the bare metal plug. This removes the risk of touching a live current source.
• Plugs should be inserted or removed from powerpacks only when the power is switched off, preferably at the wall. Ensure that the fingers do not touch the metal casing of the powerpack to avoid completing a circuit to earth. The voltage regulator should be wound back to zero after a run before removing the plugs.
• Any suspicious faults in electrophoresis powerpacks (such as malfunctioning indicator lights, damaged leads, etc.) should be reported to workshop staff immediately and the unit taken out of operation until checked and repaired.

For further information email: OHS Officer