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Recent content by wzal

  1. wzal

    Water Box Gasket Material Properties

    Any one familar with gasket material selection out there? I am specifing the material of a water box gasket with max. pressure 150 psi and max temp. 130 F. Looking for advise on the following properties: hardness per ASTM2240, Compression set 25% compressor per D395, creep relaxation. Thanks...
  2. wzal

    NEC wire sizing Q

    Thanks for the valuable input. More questions... Per UL, when the control panel of equipment is designed, do we need to size the wire according to Wiring Ampacity Table AND temperature test the wire, or do just one of the two requirments? Thanks,
  3. wzal

    NEC wire sizing Q

    Hi, folks, I have a question regarding wire sizing per NEC. UL requires hazardous voltage circuit conductors supplying one motor shall have an ampacity not less than 125% of the motor full load current rating. Does NEC have the same requirement? I found ampacity table 310-16 &17 in NEC 2005...
  4. wzal

    Oil flow switch closed

    Is there a sight glass you can use to check the oil level? Throttling the water valve on the cooling water loop, you will be able to raise the condening pressure and let the chiller run warmer. Good luck!
  5. wzal

    R-13 COMPRESSOR?

    Hi, I used R23, which is the replacement of R13 in a cascade system before. Why do you still want to use R13? I wanted to tried Suva 95,but could not get the system component. However, the ability of the compressor to handle the refrigerant is related to the pressure. If you could design a...
  6. wzal

    Hot gas bypass settings on Carrier screw chiller

    Hi, the screw compressor relies on minimum gas velocity to take the oil in the evaporator back to the compressor. If the compressor is running unloaded for extended period of time. The oil will accumulate in the evaporator. There will be not enough oil back to the compressor. wzal
  7. wzal

    Hot Gas Defrosting System Design

    Hi, I am designing the defrosting system for a box @ -18 C. I installed one solenoid valve on liquid line and another one on hot gas line. Do I need to put one valve (check valve or solenoid valve) on discharge line between compressor and condenser inlet? I checked a few books and found it was...
  8. wzal

    Pressure Relieve Valve Source

    Hi, Where could I find a pressure relieve valve with setting 15-25 psi (for air)? Thanks,
  9. wzal

    Defrost Heater Sizing

    Hi, I am designing a freezer with eletric defrost heater. Cooling capacity 1,000 btu/h at 5 F box temperature. How much is the power I should put in the heater? I know it depends on a lot of factors such as moisture of the load, defrosting cycle etc. But I need something to start with and do...
  10. wzal

    Pressure Regulating Valve Source (10-15 psi)

    Hi, I am looking for a pressure regulating valve that will keep the downstream pressure at 10-15 psi. Anybody knows where I could find it? Only small amount of nitrogen will go through the valve. Upstream pressure 100-300 psi. Thanks,
  11. wzal

    Downstream Pressure Regulator Source (10-15 psi)

    Hi, I am looking for a pressure regulating valve that will keep the downstream pressure at 10-15 psi. Anybody knows where I could find it? Only small amount of nitrogen will go through the valve. Upstream pressure 100-300 psi. Thanks,
  12. wzal

    TXV Valve Change for Refrigerant Conversion R23 to R508B

    Hi, we are planning to convert the refrigerant of a cascade system from R23 to R508B (Suva 95). Is it necessary to change the expansion valve? Thanks,
  13. wzal

    Refrigerant Oil Selection for Recip Compressor and R23

    Does anyone know whether I can use Castrol Icematic SW32 for my Bitzer 4H-25.2 (recip compressor) and R23 (HFC for cryogenic application)? Unfortunately, it is an old installation and I lost contact with the compressor manufacturer. Thanks if anyone could provide some input.
  14. wzal

    Coupling for Reciprocating Compressor

    Thank you all for your valuable input. I have a Lovejoy Jaw type and a Rex Omega coupling. Both of them have torque capacity 4 times of continuous torque of the application. But both of the 2 coupling manufacturers didn't say how much is the service factor I should use on the spec. (it seems to...
  15. wzal

    Coupling for Reciprocating Compressor

    Hi, I am designing a direct drive system including an electric motor and a 6 -cylinder reciprocating compressor. How much is the service factor I should use when I size the key and coupling hub/spider (because of the vibration)? Thanks,
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