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Almost all domestic tanks are fitted with check devices to enable the
statutory exchange of relief valves to be carried out without degassing
the tank. by design, the relief valve pushes open a check disc as it is
screwed into the check device.
These used to be supplied with taper
threads with no indication as to when the check should have been closed.
Today, these have been mostly phased out and replaced by parallel threaded
relief valves with a cross-drilled bleed hole as an indicator.
To remove the relief valve, it is unscrewed
until the bleed hole appears above the check valve and the gas escape
stops. this signifies that the the check disc has closed and the valve can
be further unscrewed to remove it.
If the check has not closed and gas is
still venting, the check valve is faulty. When this occurs, the relief
valve must be screwed back into the check device and the tank degassed to
allow the complete assembly to be changed.
If the relief valve is removed and the
check has not closed, tank pressure will eject the relief valve under
great force and there will be considerable loss of gas. Under these
circumstances, any attempt to refit the relief valve quickly is futile,
due to the force of the gas escaping from the tank. This is a major incident. |
On
above ground tanks, the relief valve can be viewed quite easily and the
appearance of the bleed hole is obvious but, on underground tanks, this is
not the case and, more importantly, the operator's head is now above the
relief valve, so any mistake results in possible injury to the operator.
So what can be done? Mirrors can be used,
but this is not satisfactory when gas is venting into the chamber and the
operator has his face over it to view the
Re-Manufacturing Services Ltd (RMS) has
come up with a solution that solves the problem. A split collar with
sleeve is fitted over the valve, stopping the relief valve from being
unscrewed past the vent hole. When the relief valve hits the stop, if the
check has closed, it can be removed and the relief valve removed.
There is a unit to suit all the common
valves currently used in the UK, and all are clearly marked with the valve
type to ensure they do not get mixed up. If they do get mixed up or the
wrong tool is tried on a valve, it will not fit, so it is virtually idiot
proof, says RMS.
Contact Re-Manufacturing Services Ltd on 01792 898008 |
