Pump Selection for Hms and Hmd - What's the Difference?

In summary, the relation between Hms and Hmd and pump selection is that Hms is the suction head of the pump, while Hmd is the discharge head. The difference between these two values, known as Hm, is the maximum vertical height or head that the pump can produce. The pump's discharge head, or Hmd, is only 2 bars, while it can withstand pressures up to 12 bars. This means that the pump is capable of operating in a variety of circumstances, including taking liquid at 10 bar and spinning it up to 12 bar. This results in a higher maximum vertical height, or head, for the pump. Therefore, the pump can be used in both closed and open systems, depending on
  • #1
tell me guys what's the relation between Hms and Hmd and the pump selection for example
i have Hms =10bar , Hmd =12 bars so Hm =2 bars
so the Head of the pump is only 2 bars or its said that
pump has a head of 2 bars and can withstand 12bars ?
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  • #2
Well, unless 12 bars is the maximum operating pressure, then that isn't your limit but yea, the "pump head" is 2 bar, about 30psi and around 67 ftH2O.

But the liquid you are pumping will exit the pump with a total of 12 bar (175 psi, 405 ftH2O)
  • #3
so the pump is a normal pump ?
  • #4
? I don't think I understand the question?

I assume this is a centrifugal pump? In which case yes, pumps can operate in any number of circumstances, one such "normal" operation is taking water under pressure (say, 10 bar) and spinning it up to 12 bar.

Hms is the suction head of the pump. I don't mean to sound pedantic, but do you know what head is? If you do disregard this next couple of sentences. Your 10 bar (~335 ft of head) is the height in feet that the water (or whatever medium, after accounting for SG) would rise to if you piped it straight up. The pump takes this water and spins it with the impeller, giving it a higher velocity. This higher velocity creates a vacuum between the faster liquid and the slower stuff at the suction port. This, combined with the pressure already imparted on the water at the suction (the 10 bar), sucks the water into the impeller to be propelled, continuing the cycle.
The energy imparted on the water by the pump results in a higher maximum vertical height, or head. Thus, higher pressure.
  • #5
yes ur very right
u know the pump has high Hms and Hmd but normal Hm and the pump will give speed to water yes correct
i think its an ordinary pump not special pump
because these 10 bars after operating the pump it will reduced by the value of vacuum created by pump impeller
do u faced this problem before ??
  • #6
I don't see a problem. I see a pump operating exactly as it should. Taking liquid of one pressure, adding energy, and discharging the liquid at a higher pressure.

As I said, if your pump is taking a liquid at 10 bar and spinning it up to 12 bar then you have the following situation:

1) A pump that has a discharge head of 2 bar.
2) A pump that is designed to withstand and internal pressure that is greater than 12 bar.
  • #7
It is for a closed or an open system ? Why don't you look at the pump curve?

1. What is the difference between HMS and HMD?

HMS stands for Head, Motor, and Shaft while HMD stands for Head, Motor, and Discharge. The main difference between the two is in the discharge component. HMS pumps have a horizontal discharge while HMD pumps have a vertical discharge.

2. Which type of pump is better for my application, HMS or HMD?

The choice between HMS and HMD pumps depends on the specific requirements of your application. HMS pumps are more suitable for applications with low flow rates and high head pressure, while HMD pumps are better for high flow rates and low head pressure.

3. Can I use the same pump for both HMS and HMD applications?

No, HMS and HMD pumps are designed for different types of applications and cannot be used interchangeably. Using the wrong type of pump can result in reduced efficiency and potential damage to the pump.

4. What factors should I consider when selecting a pump for HMS or HMD applications?

Some important factors to consider when selecting a pump for HMS or HMD applications include the required flow rate, head pressure, type of fluid being pumped, and the operating environment. It is also important to consider the pump's efficiency and maintenance requirements.

5. Are there any other differences between HMS and HMD pumps besides the discharge orientation?

Yes, in addition to the discharge orientation, HMS and HMD pumps may also differ in terms of their overall design, construction materials, and operating speed. It is important to carefully compare the specifications of each pump to determine which one is best suited for your specific application.

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