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Thread: Metric pump data - anyone familiar with the terminology?

  1. #1
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    Metric pump data - anyone familiar with the terminology?

    so here's the pump data


    Power: 0.75KW
    Flow: 3T/h
    Head of delivery: 16m

    power and head are easy, but what's the flow? never seen a "T" before, i can only assume it means Ton? like a 1000kg metric ton? which would mean theoretically 1000 liters, which i think is like 250 gals.

    lots of guessing there, but is that what they're saying? so max flow is ~250gals/hour at 0 head?

  2. #2
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    Power in kW is just another way of saying how much work the pump can do, similar to HP. The flow does appear to be Tonnes/hour, which in SI units is equivalent to 3000L/hour of water at STP(room temperature, sea level) roughly 792 gallons per hour. 1L of water is 1kg, so 3000L is 3000 kg, or 3 Tonnes. Head of delivery, I would guess that it is the same as Max head, 16m is 52.5 feet.
    Quote Originally Posted by brain medicine View Post
    so here's the pump data


    Power: 0.75KW
    Flow: 3T/h
    Head of delivery: 16m

    power and head are easy, but what's the flow? never seen a "T" before, i can only assume it means Ton? like a 1000kg metric ton? which would mean theoretically 1000 liters, which i think is like 250 gals.

    lots of guessing there, but is that what they're saying? so max flow is ~250gals/hour at 0 head?

  3. #3
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    Kent, WA
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    See if you can get a pump curve from them. Regardless of the units, it will help tell you how the pump will perform at various discharge heads. For example, Jebster is probably right that max head is 16m, which means the flow rate is near zero at 16m head. 3 T/hr is probably the rating at open discharge (e.g. zero head)...but we're just guessing.

    Sometimes you can get different impellers on a pump that will have different flow/head characteristics.

    Regards,
    Mike

  4. #4
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    no pump curve. hence the question posed. good catch by jebzter, forgot to multiply by three tonnes, not one. digging through their info i actually found that it is in fact tonnes and it equals cubic meter per hour, which is the 264 gals/hour or 4.4 gals/min. so i made a straight line graph using no flow at max head and max flow at no head.

    my HX is rated a ~2psi drop (4.4 hd ft), full tank is about 6 feet high, plus hoses and fittings and lets call it a dozen head feet to fill the tank?

    at a dozen head feet the 1hp motor is roughly 11gals/min, so i'd be running pump at roughly 23% power by vfd. but it would be more like 20% when i pump the first batch into empty tank.

    now they also have a 1/2hp 1T unit that would be doing just about 2.5 gals/min at that same dozen ft head height. so i'd be running it a little bit slow on first batch, then almost full power by second batch.

    i'd prefer to try the 1hp as it seems like not only could it transfer but also have enough power to spin my CIP balls. but my worry is that at only ~20-23% power from the vfd, the motor might not even spin when im trying to transfer. takes a certain amount of torque to get it to kick over.

    am i being too cautious there? does 20% power seem like it should be enough to get a motor turning?

  5. #5
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    Your VFD settings should not reflect power, but RPM. So from the 20hz to 60hz, the RPM will vary and thus the flow. Torque should be constant and at maximum through the whole curve. There are various types of VFD control, most units can run either constant torque or variable torque, and even can provide up to 150% of rated torque at the starting speed. So you shouldn't see any problems with this at all, assuming your VFD is properly configured.

  6. #6
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    Great. I assume constant torque makes most sense in this application. Hopefully that matches the unit we already have on hand.

    Thanks jebz, i owe you some cold ones if you come to the city.

  7. #7
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    For a centrifugal pump set the VFD to variable torque and for a PD pump set it to constant torque.
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  8. #8
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    Thanks. I misunderstood the premise, thought it was an either/or situation with the vfd. Ill be sure to verify unit can do both.

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