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  1. dcasto

    Dehydrator Mass Transfer Zone and Beds Life Calculation

    the general rule of thumb is mole sieve beds can hold 15% by weight of water
  2. dcasto

    Two stage compressor

    The compressor manufacturers even have dummy cylinders where the compressor may require just 3 throws so the 4th throw has a dummy weight to balance the forces on the unit. Since the weight will not change on the throw you "crippled" and crippled is an actual technical term here, there is...
  3. dcasto

    Two stage compressor

    Yes, you can pull the suction valves out of one head of the compressor. You know that the unit will be a single stage and subject to higher differential and high rod loads and high discharge pressures
  4. dcasto

    Flow rate not fulfilled in revamped recip compressor

    Time or some actual run data to be taken. What is the actual discharge temperature, if its way over the 216, then that indicates broken valves or excessive valve loss. If you run the compressor at 20 psig suction and 95F, you get close to the 2 MMSCFD. Now instead of the 216 F, there would be...
  5. dcasto

    Fire case scenarios

    Run the fire case scenario along with all credible scenarios. 99% of the time in process vessels and piping have other cases where the PSV for the system has one of the other scenarios controlling the size. The fire case is usually the controlling factor for storage vessels and with spill...
  6. dcasto

    Gas compressor Cold Gas Bypass valve sizing question

    I'll make the leap of faith, cold gas by-pass is the start up bypass system to assure the driver is not being loaded beyond its available torques as it starts movement. If that's what you are indicating, then its easy to match driver torque output versus speed against the compressors torque...
  7. dcasto

    Max Differential Pressure Across An On/off Valve Prior To Open It

    Its more of a torque required to open it. But the 15 to 30 isn't that much differential on a 4" valve, on a 24" valve its a lot. As stated above there is either water hammer or in most cases, what is downstream. In a facility where a sudden surge is going to lift the bed in a reactor, slam...
  8. dcasto

    We have a PSV that has been popping

    use a pilot operated set 10% higher than the desired MAOP if you cant tune the compressor surge controls better.
  9. dcasto

    Determine pressure drop of RO in minimum recirculation line

    The problem I see with your diagram is that the exchanger in the line will either heat up the inlet tank or cool it, not sure the duty direction. Unless the fluid is terribly full of junk to be filtered, put the min flow RO just around the pump(s).
  10. dcasto

    LPG piping code

    In the US, the regulations let the owner decide, 31.8 Or 31.4, then follow the rules of whatever you decide. For example, in the late 70's my company built a line for ethylene under gas, every line we interconnected to was classified liquid, how can that be? Under liquid codes, the debating...
  11. dcasto

    ASME vessel stamp with REST pressure

    We have a Gas Chiller with a stamp that reads Temperature -50/150 Pressure 100/250 REST pressure 350 psig. The vessel is dated 1981, I know it isnt SA214 that had serious issues with low temperature. Since the chiller fluid is propane and the minimumtemperature cant really get to -50 without...
  12. dcasto

    Parellel Pumping

    The don is right, pumps control nothing, the system controls the pumps! Oh, that's what my coworkers call a Decastoism, no, it's just the fan laws.
  13. dcasto

    Pipeline Test Head

    Next are we going to toss out a paddle blind on a test because it saw its max pressure 1 time? Zdas is spot on! The life cycle of a a flange cycle is around a million times, now, the bolts and gasket? The bolts a few hundred thousand, the gasket a few times, toss them Oh, does this mean all...
  14. dcasto

    Process design

    120 km of line? The line is at temperature equilibrium in 10 km, so hydrates at a stopped flow is not the issue? Etop is correct, what is the issue?
  15. dcasto

    design of raciprocating gear pump

    A gear pump is nearly linear on output versus head, look into gear pump suppliers in your area, it's an easy job, almost gear pumps like viscous fluids and higher heads I'd look at a common ANSI pump.
  16. dcasto

    Air conditioned air for compressor suction

    I did studies to use the propane refrigeration system to cool the inlet air to the gas turbine running the refrigeration compressor, a 5 stage centrifugal. Guess what, it wins, the output energy from the turbine went up faster than the energy used to cool the air intake. You ask what does that...
  17. dcasto

    Orifice meter max differential pressure maximum question

    Hidden in the report 3 is a table with ratio of dP/press. If that ratio is too high, the equations fall apart. The Y factor compensates for density change at high dPs.
  18. dcasto

    Booster pumping in series questions

    We run two pumps in series, the second pump on a VFD for flow control, works great.
  19. dcasto

    Blowdown for compressor restart

    No where does the term blowdown mean 100% evacuation of the compressor. Just like no where does it define the time to 100% depressurization.
  20. dcasto

    BTEX Solvents Ban

    Xylene isn't banned, the regulations and paper make it expensive. Under CA prop 65, all new cars have a warning label saying that cars have crud and other street language terms that are dangerous. Coca cola reformulated its carmel coloring because some ppm of a burned sugar is dangerous.

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