# Flowrates in gravity system + piston pump

• dutchbomb
In summary, when trying to model an elevated vat using gravity to supply water to a filler, it is important to calculate the headlosses and available head to ensure that there is enough pressure to supply the required flowrate to the filler.
dutchbomb
Hi all

I hope you can help me here. I am trying to model an elevated vat which is using gravity to supply water to a filler. The pipeline has filters and bends in it which lead to headlosses. The filler supplys a fixed volume of liquid to a bottle at set time intervals. The filler is basically a glass jar (of sorts) with a piston in it and every time it needs to fill a bottle the psiton moves up - thereby pulling water into it. Once it has been filled the inlet valve shuts, oulet valve opens and the piston moves down - thereby filling the bottle.

I previously calculated the flowrate of a simillar system assuming it was one vat draining into the other. Here i wrote all sources of headlosses in terms of Q, summed and equated these to the total available head and solved for Q. This was a straightforward method which provided me with good results.

However, with the inclusion of the filler and the suction head it provides at intervals I'm not sure how to calculate the flowrates. Essentially i am looking to see if there is enough head available to supply the filler with enough water.

Your thoughts are appreciated!

</code>One possible approach is to calculate the headlosses for each component in the system, then deduct these from the total available head. For example, if the total available head is 10m, and you have calculated that the filters and bends cause a total headloss of 2m, then this leaves 8m of head available for the filler. You can then calculate the flowrate required to fill the bottle in a set time interval (e.g. 60 seconds) by dividing the volume of the bottle by the time interval. This should give you an idea of how much water needs to be supplied to the filler in order for it to fill the bottle in the given time. You can then compare this with the available head of 8m to see if there is enough pressure to supply the required flowrate. If not, then you may need to consider other solutions such as increasing the total available head, or changing the configuration of the system to reduce the headlosses.

## 1. What is the purpose of a piston pump in a gravity system?

The piston pump is used to increase the flow rate of a gravity system by creating pressure and pushing the fluid through the system. This is especially useful for systems with long or uphill pipelines where gravity alone may not provide enough force to move the fluid.

## 2. How does the flow rate in a gravity system with a piston pump compare to a gravity system without a pump?

The flow rate in a system with a piston pump will be higher due to the added pressure and force created by the pump. However, the exact increase in flow rate will depend on factors such as the size and power of the pump, as well as the length and slope of the pipeline.

## 3. What factors can affect the flow rate in a gravity system with a piston pump?

The flow rate in a gravity system with a piston pump can be affected by a variety of factors, including the size and power of the pump, the diameter and length of the pipeline, the viscosity and density of the fluid being pumped, and any obstructions or restrictions in the pipeline.

## 4. How can the flow rate in a gravity system with a piston pump be optimized?

To optimize the flow rate in a gravity system with a piston pump, it is important to select a pump that is appropriately sized and powered for the specific system and fluid being pumped. Additionally, minimizing any obstructions or restrictions in the pipeline and maintaining proper maintenance of the pump can help optimize flow rate.

## 5. Are there any limitations to using a piston pump in a gravity system?

While a piston pump can greatly increase the flow rate in a gravity system, there are limitations to its use. These can include the cost of the pump, potential maintenance and repair needs, and the potential for pump failure. Additionally, the pump may not be able to overcome certain physical limitations such as extreme pipeline length or steep slopes.

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