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Mechanical seal monitoring system ?

  1. May 19, 2010 #1
    mechanical seal monitoring system ????

    hello everyone
    i have a system consists of A blower used for nitrogen cooling
    this blower has a mechanical seal which is cartidge seal and the seal cooling liquid is water
    pumped from a water tank via a water pump to keep both surfuces of the seal blanced under 10 bars each one face is for water and the other is for nitrogen the questions is ????????????????????

    1- what will happen if i run the seal with smaller pump which has smaller head than the big pump????
    2- the mechanical seal cooling system contains a flow meter " safe unit " john crane this flow meter has a pressure switch to ensure that the blower is running only if the cooling pump is working an realized its pressure so
    what if i replaced this safe unit with a flow control valve with a normal pressure switch ????
  2. jcsd
  3. May 19, 2010 #2


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    Re: mechanical seal monitoring system ????

    Hi maxx. Why do you need the 0 psi dP across the seal when it's running? As I understand it, you have the 10 bar nitrogen on the one side and 10 bar water on the other side of the seal for cooling. Is that right? Does the seal get that hot that you need a coolant? Do you need the water pressure to be the same as the nitrogen pressure or do you just need the right cooling water flow rate?

    I've seen plenty of seals that need close to 0 dP and they generally use a pressure switch, but if your seal needs cooling water flow, then maybe both are necessary.
  4. May 19, 2010 #3
    Re: mechanical seal monitoring system ????

    THE main problem is if i dont have the monitoring system which is the flow meter with the pressure switch can i replace this manually and what if i need the correct flow rate of coolant of the seal ???
  5. May 19, 2010 #4


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    Re: mechanical seal monitoring system ????

    Do you have the nitrogen at high enough pressure available? John Crane uses many setups with supplied nitrogen and needle valves for simple flow control.

    I would imagine there's a reason that a blower was used as opposed to a very cheap and simple needle valve/regulated nitrogen setup.

    Do you just want to control the pressure or do you want to try and control the flow (really on seals you'd more likely monitor the flow to see changes in seal leakage). If you just want to control the pressure and have pressurized nitrogen available without the blower you can use a pressure regulator. If the cooling water pressure may change then you can reference the regulator to it.
  6. May 19, 2010 #5
    Re: mechanical seal monitoring system ????

    can u send me some technical notes on mechanical seals ?? i want to be proffissional with this
  7. May 19, 2010 #6
    Re: mechanical seal monitoring system ????

    well i have a new idea of removing the flow meter and pressure switch also and use
    nitrogen from the blower outlet to pressurize the cooling fluid
    is this will be effiecinet
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