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  • Users: themroc
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  1. themroc

    how to fit a correlation to meassured data in excel

    In the attached excel sheet (interpolation.xls) measured friction factor data are shown as a function of Reynolds. The data are for different packing densities. 30 = lowest packing 80 = highest packing. As it can be seen the values are strongly decreasing with higher Reynolds number. Applying...
  2. themroc

    condenser capacitor / capacity measurment working principle

    Thanks for the answers. In principle I agree with itsmoked. A direct meassurement is defenitely better. But in this case a direct meassurement takes very long and if the resistance meassurments gives an indication than we could use this for screening purposes. Do you think it would work to...
  3. themroc

    condenser capacitor / capacity measurment working principle

    I am working for a company which manufactures turbulators to improve the efficency in tubular heat exchangers. A sketch of those Inserts can be found here: http://www.calgavin.com/hitran/hitran.htm Those turbulators induce turbulence near at the tube wall and therefore improve the heat transfer...
  4. themroc

    Motor Overtemperature

    Does it in general mean that a hot motor draws more Amps and therefore it would trip at a certain condition?
  5. themroc

    Motor Overtemperature

    I am running a gear pump using a Siemens micromaster FI Inverter. The gear pump is connected to a 4kW Motor. The pump is part of a test rig, at times it is required to run the pump at very low speeds/frequencies. Under this situations from time to time I encounter a FI cut out due to...
  6. themroc

    Output reading Load cell

    Why would a voltmeter not do the same job. I was intending to use a data aquisition system, which I think takes readings in this range to record the loads? :)
  7. themroc

    Output reading Load cell

    That would mean 100lbs = 30mV 50 lbs = 15mV 1 lbs = 0.3mV Is this right? :)
  8. themroc

    Output reading Load cell

    We are in the process of purchasing a load cell in order to meassure tension force. The Excitation Voltage is 10 VDC and it states Rated Output (R.O.): 3 mV/V nominal We are interested in the 100 lbs capacity range. Would that mean at 100lbs my output signal is 10V How do I have to interpret...
  9. themroc

    wrong run direction on 3 phase pump motor

    Thanks to all, I got it working and did not use the earth cable :)
  10. themroc

    frequency inverters to controll flow rates

    Thanks gepman, I will consider this and post it maybe there. Only one stupid Question, what does PWM and VFD stand for? One other think, All my signals are 4 to 20mA except for the temperature sensors which are T-Type thermocouples and 4 wire PT-100. The cables of all instrumens are shielded is...
  11. themroc

    wrong run direction on 3 phase pump motor

    I connected a 3 phase motor of a centrifugal pump (0.75 kW) After connection it turned the wrong way round. My connection is the following W2 ----- U2 ----- V2 U1 ----- V1 ----- W1 | | | R S T Which cables do I need to change in order to change the...
  12. themroc

    frequency inverters to controll flow rates

    Instead of using control valves in order to control the flow I intend to use Frequency inverters to regulate the motor speed of a centrifugal pump (2.2kW) With this type of controll I had quiet good experience in the past. Now my Question: The FI Inverters I intend to use are Siemens...
  13. themroc

    controll switch for solenoid valve

    Thanks OperaHouse, good recommendatyion but we have got already the 24VDC power supply. Just one Question you say the diode has to go in parallel. Just to claryfy. I would connect the + from my DC Power supply to the + of the SS relay and than to the + of the solenoid valve and I presume the...
  14. themroc

    controll switch for solenoid valve

    The valve is 24VDC. With this voltage it is rated at 12W. I was investigating what kind of Diode to use and where to connect to, but the information out there for a non electronic expert is quiet owerwhelming. So maybe someone of you can help. What kind of Diode do I need for this application...
  15. themroc

    controll switch for solenoid valve

    Thanks scottyUK, that sounds good. Where exactly do I connect the diode to. I presume I will have a plus and minus on the relay load output to my solenoid, do I have to connect the diode inbetween the plus connection or does it not matter. What kind of Diode specification do I need? (I just...
  16. themroc

    controll switch for solenoid valve

    Just a Question to the experts, would this one do the job: http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=3776097 Thanks Peter
  17. themroc

    controll switch for solenoid valve

    Thanks, I was told that I should go for a solid state relay in order to avoid backcurrent??? What is the principle of both relay types??
  18. themroc

    controll switch for solenoid valve

    A stupid Question for a electrical engineer, but it comes from a chemical engineer. I intend to switch a solenoid valve on/off. To do this I have got a data aquisition module here I can trigger 0 or 10 Volts output. The solenoid valve I have got is switched by a 24Volt signal (0 vot closed /...
  19. themroc

    Sound protection for gear pump

    Thanks for your answers. Just a comment. We use a flexible corrugated SS metal hose to connect from the gear pump to the rest of the tubing. We can not use normal hose due to the fact that we have got up to 15 bar pump pressure. I will have a look whether decoupling is possible. But the pump...
  20. themroc

    Sound protection for gear pump

    We are using a gear pump in a research Lap in order to pump thermal oil for a test rig with different rotational speeds. At high gear speed the sound of the pump motor is quiet loud. Does anyone know companies which offer sound protections (probably pump encapsulations) in order to reduce the...

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