Break & Seating Torques, Are they Equal?
Break & Seating Torques, Are they Equal?
(OP)
I will like to put this question out to all valve engineers, in hope of a valued explanation:
1. For a conventional butterfly v/v, is the breakaway & seating torques equal?
2. What equations/formulae can be used to relate the relevance of these 2 torques?
I will be grateful if there is anyone who will spare some time to reply my question.
Thank you for reading.
Jerri
1. For a conventional butterfly v/v, is the breakaway & seating torques equal?
2. What equations/formulae can be used to relate the relevance of these 2 torques?
I will be grateful if there is anyone who will spare some time to reply my question.
Thank you for reading.
Jerri





RE: Break & Seating Torques, Are they Equal?
For Shaft Downstream:
i. torque tp close v/v is given by:
Tseat= -Tpacking -Tseat -Thandwheel -deltaPmax(bearing torque factor + off balance torque factor)
ii. torque required to open v/v is:
Tbreak= +Tpacking +Tseat +Thandwheel +deltaPmax(bearing torque factor - off balance torque factor)
For Shaft Upstream:
i. torque tp close v/v is given by:
Tseat= -Tpacking -Tseat -Thandwheel -deltaPmax(bearing torque factor - off balance torque factor)
ii. torque required to open v/v is:
Tbreak= +Tpacking +Tseat +Thandwheel +deltaPmax(bearing torque factor + off balance torque factor)
Can anyone throw some light on it?
THANKS.
RE: Break & Seating Torques, Are they Equal?
RE: Break & Seating Torques, Are they Equal?
Naturally the manufacturers will try and keep these values as low as possible but they will be different from valve design to valve design and seating material to seating material.
The seating and breakout torques are not necessarily the same indeed breakout can be time dependent, depending on the seat design and can increase with time.