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  1. jbattershell

    Motor water to air heat exchanger tubes - 70/30 or 90/10 CuNi ?

    tube material is selected based on the water conditions and the expected fouling/corrosion. copper tubes are best for coolers if the water is not prone for high corrosion or fouling. next step up in corrosion resistance is generally the 90/10 tubes and that should provide most users sufficient...
  2. jbattershell

    Dew Point Management in Oil Flooded Screw Compressors

    there isn't a way to control water content or "dewpoint" to any meaningful way in this screw compressor unless you are cooling and reheating the discharge air. even if the discharge temperature of the compressor were kept high enough to be above the dewpoint, you still have a bunch of water in...
  3. jbattershell

    Threaded Thermowell On Discharge of Centrifugal Compressor

    API-614 advises that for pipe threads used on systems with hazardous fluids over 75psig operating pressure, all threads shall be seal welded. sound advice is to use flanged thermowells for piping containing flammable gas or toxic gas. if you use a threaded thermowell, i would seal weld it...
  4. jbattershell

    Surge and stonewall of centrifugal compressors

    the control system may have been working properly and attempted to open blow off valve when the compressor reached the surge line, but the valve may not have opened due to being stuck. you would have to look at the history data (if available) to see if the signal was given to the valve at the...
  5. jbattershell

    Load Sharing between 2 Nos. Centrifugal Compressors of Different Capacity and Discharge Pressure

    if both compressors are connected to the same discharge header, the maximum discharge pressure in that header is limited to what the lower pressure rated compressor can reach (27kg/cm2). the other compressor with a higher discharge pressure must operate at its normal design pressure (or close...
  6. jbattershell

    API definition of string test for compressors

    RotaryW, API-617 would suggest that the OEM tests all auxilary equipment during the mechanical test of the compressor. the Fact is that this is rarely done. in the description of the test procedure which has been given to the customer, it is usually described what equipment is and what isn't...
  7. jbattershell

    Capacity Control Methods

    inlet throttling using a pressure reduction device like a butterfly valve will of course throttle the compressor effectively. however, it gives up efficiency for cost. an inlet guide vane will first throttle the compressor by pre-swirling the air/gas to the first stage. this effectively...
  8. jbattershell

    Air Cooled Centrifugal vs. Air Rotary Screw compressors

    the air cooled centrifugal compressor that I am familiar with will operate reliably in ambient temperatures of 105-110F. the after cooler is in most cases, a 10degree approach cooler. this compressor is integrally geared. it will have longer life cycle than dry screw, higher efficiency, and...
  9. jbattershell

    Lube oil system reliability-Kindly guide

    I have designed many compressors with shaft mounted main oil pumps. I re-designed a number of them with better couplings since that was one of the failure points. an electric motor driven aux pump will allow the compressor to start up with full oil pressure and will allow the compressor to...
  10. jbattershell

    two centrifugal compressors in parallel

    a simple way to run two centrifugals in parallel: set one machine with a pressure set point approximately 5psig higher than the other machine. the unit with the higher set point will eventually be running full out, trying to reach the higher pressure set point. the other machine will be...
  11. jbattershell

    Is a countersunk flathead screw in and of itself a locking fastener?

    I have personal use with a bunch of flat head screws in high vibration application. if the fastener is not loctited, they will come loose. In my proffession, it has been used, with success, peening of the fastener to lock it in place. a punch is used and the very edge of the fastener is...
  12. jbattershell

    Check Valve downstream Anti Surge Valve

    then you should remove that check valve. it is not needed. the recycle line should only contain the recycle valve and in many cases, a diffuser or silencer to reduce the noise level of the valve during operation. the requirement of the silencer is usually dictated by the vendor supplying the...
  13. jbattershell

    Check Valve downstream Anti Surge Valve

    MortenA, what you are describing is a discharge check valve. And you are correct, that check valve is needed and has always been installed in the final discharge line from a centrifugal compressor. however, the literal meaning of "check valve downstream of the recycle valve" means to me...
  14. jbattershell

    Check Valve downstream Anti Surge Valve

    I have never put a check valve downstream of a recycle valve in 25 years of designing centrifugal compressors. it is not needed. if you want to provide more detail on the actual arrangement of piping and the process, maybe there something strange with your installation than can be assumed...
  15. jbattershell

    Dry Gas Seal pressure controlled

    alarm on primary seal flow supply. whether to also have a trip on low low supply is up to the user and the process criticality. secondary seal also has to have protection. supply flow meter on N2 supply to secondary seal. flow meter on primary vent. compare the two values in the controls...
  16. jbattershell

    Non-API Compressors

    some OEM compressor suppliers can provide what I would call an API-617 lite. that is, the really necessary parts of API are included like the special shaft seals and such, but other parts which are not as important are not included. some of those other things can be as simple as not including...
  17. jbattershell

    Key things to look out for Centrifugal Compressor Selection

    selecting compressors for an application, you should leave many of those items listed above to the actual OEM. items such as number of stages, mach number, gas temperatures are to be figured out by the experts at the OEM. you need to be focused on getting the correct flow and pressure...
  18. jbattershell

    Non-API Compressors

    If the compressor is going to be compressing a flammable or hazardous gas, API-617 will need to be followed, as well as the applicable electrical codes such as NEC or IEC that deal with hazardous areas.
  19. jbattershell

    Mech'l Running Test of multistage Cent Comp as per API 617

    Raphatss, testing was done with both air compressors and gas compressors. most tests were type II. Gas compressor, type II tests were conducted with inert gas. speed was similar to full speed during the aerodynamic testing, but not right on. most times, the inlet temperature could be...
  20. jbattershell

    Mech'l Running Test of multistage Cent Comp as per API 617

    CaracasEC, you are right, the API-617 code does not specifically state that the mechanical test shall be conducted under load. However, section 4.3.8.6 does specify that a full pressure, full load test can be conducted by the OEM and that this test procedure should be agreed upon between the...

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