 |
| |
Reg. 291, Reg. 292
SPECIAL REQUIREMENTS
Safety Valves
General
|
| |
| Safety valves, ordinary,
high lift and full lift, shall be so constructed that
breakage of any part will not obstruct the free and full
discharge of steam from the boiler. |
Reg. 292
Definition
| a) |
Ordinary lift safety
valve: A safety valve in which the valve head lifts automatically
a distance of at least D/24 with an over-pressure not
exceeding 10% of the set pressure. There shall not be
any mechanical stop which would prevent the valve head
from being lifted a distance of at least D/8. D is the
minimum bore of the Body seat. |
| b) |
High lift safety
valve: A safety valve in which the valve head lifts automatically
a distance of at least D/12 with an over pressure not
exceeding 10% of the set pressure. There shall not be
any mechanical stop which would prevent the valve head
from being lifted a distance of at least D/8. D is the
minimum bore of the Body seat. |
| c) |
Full lift safety
valve: A safety valve in which the valve head lifts automatically
a distance such that the area of discharge which limits
the flow through the valve is between 100% and 80% of
the minimum area at any section at or below in body seat.
This lift is achieved by a rapid opening within an over
pressure not exceeding 5% of the set pressure. |
|
|
