Reg. 300, Reg. 301, Reg.
302, Reg. 303
|The valves and spindles
shall be efficiently guided and means shall be provided
in every case to prevent their lifting out of their guides.
The working parts shall have sufficient clearance to ensure
freedom of movement under all conditions of service. The
spindle shall not be fitted with a stuffing box.
Bearings for Levers
|The bearings of the
levers of lever valves shall be so designed as to allow
of free working of the valve under all conditions of service.
Where the lever is mounted on pin bearings, the holes
in the lever shall be bushed with non-corridible metal,
or the pins shall be of non-corrodible metal.
Attachments of weights and Springs
||In a lever and weight
safety valve the weight shall be in one piece and attached
to the lever in such a way that the safety valve cannot
In the case of spring loaded safety valves, washers
or ferrules shall be fitted under the adjusting screws
so that the valves cannot be overloaded when under steam.
Interference with load on the spring, after the safety
valve has been adjusted, shall be prevented by the fitting
of a ferrule under the adjusting screw collar or by
using a lock nut on the adjusting screw which shall
be further safeguarded by means of a padlock or other
suitable device. Where springs are in tension, links
or other suitable stops shall be fitted to prevent the
spring being extended a greater amount than that corresponding
to a valve lift of D/4.
where D=diameter of valve seating.
|Safety valves shall be so arranged
that they can be eased off their seats when under pressure
and the easing lever shall positively lift the valve.