kjvaughn
Chemical
- Oct 18, 2006
- 2
I have a problem a flowrate that I am trying to estimate without the use of a metering device.
The setup that I am dealing with involves an upstream gate valve that isolates the downstream control valve (Valtek angle valve) that vents to atmosphere. These two valves are in service with 660# steam service, and are used to vent of excess 660# steam in the case of an upset. There is a small 3/4" bleeder in between the gate valve and the control valve.
I am in charge of trying to come up with the credits (amount of steam lost due to the leak) for repairing this system. The gate valve is also leaking, so we can't just close the gate valve and replace the control valve. We are looking a doing a on-line line stop.
What I am trying to do, and need help with, is determing the flow through the gate valve (when completely closed) and how much is flowing through the control valve when the gate valve is open, which is normal operation.
I did some testing and put a pressure gauge on the bleeder, and completely closed the gate valve, then we opened the control valve to 100%. We went down in 5 % increaments and I registered the pressure on the gauge.
The pressure ranged from 1 PSIG to 100 PSIG (when the contol valve was almost completely closed).I know the Cv of the control valve. I thought I could calculate the leak by rate of the gate valve and used the pressure reading to find the equivalent orifice size thatis leaking by the control valve thereafter.
Does anyone have any ideas on how to calculate the gate leak-by rate and then calculate the leak-by rate when the gate valve is completely opened and the control valve is closed??
I appreciate any help!!!
Kyle
The setup that I am dealing with involves an upstream gate valve that isolates the downstream control valve (Valtek angle valve) that vents to atmosphere. These two valves are in service with 660# steam service, and are used to vent of excess 660# steam in the case of an upset. There is a small 3/4" bleeder in between the gate valve and the control valve.
I am in charge of trying to come up with the credits (amount of steam lost due to the leak) for repairing this system. The gate valve is also leaking, so we can't just close the gate valve and replace the control valve. We are looking a doing a on-line line stop.
What I am trying to do, and need help with, is determing the flow through the gate valve (when completely closed) and how much is flowing through the control valve when the gate valve is open, which is normal operation.
I did some testing and put a pressure gauge on the bleeder, and completely closed the gate valve, then we opened the control valve to 100%. We went down in 5 % increaments and I registered the pressure on the gauge.
The pressure ranged from 1 PSIG to 100 PSIG (when the contol valve was almost completely closed).I know the Cv of the control valve. I thought I could calculate the leak by rate of the gate valve and used the pressure reading to find the equivalent orifice size thatis leaking by the control valve thereafter.
Does anyone have any ideas on how to calculate the gate leak-by rate and then calculate the leak-by rate when the gate valve is completely opened and the control valve is closed??
I appreciate any help!!!
Kyle
