# Pump water from multiple tanks under vacuum by common pump?

• rollingstein
In summary, the conversation discusses the possibility of using a common pump and suction header to pump out water from three tanks with different vacuum levels into a single tank at atmospheric pressure. The flow rates, line lengths and sizes, and placement of the pump are all flexible. The conversation also mentions the use of check valves and the potential issues with backflow and cross contamination. The conversation then shifts to a discussion on compressing air at different altitudes and the energy required for the process. Finally, the conversation concludes with a question about the equilibrium of pressure in the three tanks.
rollingstein
Gold Member
Is it possible to pump out water from three tanks all under a different vacuum level using a common pump and common suction header? Or would this arrangement cause problems? The destination is a single tank at atmospheric pressure.

See Sketch below.

I'm trying to intuitively figure how the pressure profile in the piping would look like.

Flow rates? Line lengths and sizes?

Bystander said:
Flow rates? Line lengths and sizes?

Tanks are all next to each other. Line length is approx. 100 ft total from anyone vacuum tank till the atm tank. Where to keep pump etc. is flexible. All three vacuum tanks are elevated approximately 10 feet above the atmospheric tank.

Flow rates are low; approx. 500 Litres/hr from each tank. Line size is flexible too but I was thinking 1/2 inch would be generous.

Basically, three condensate accumulations have to be emptied out & I was wondering if I could do with one pump instead of three separate ones.

rollingstein said:
10 feet above the atmospheric tank.
Check valves on the exit lines? One and two are going to be self-draining, and three is the only one that will require pumping.

Bystander said:
Check valves on the exit lines? One and two are going to be self-draining, and three is the only one that will require pumping.

Makes sense thanks.

Out of curiosity what if the vacuum levels were stronger. i.e. none of the tanks were self draining. Would this pumping scheme work then?

Say assume 300, 200, 100 mmHg?

I'm always hesitant to count on a gravity head for draining. That's why a pump would give me a margin of safety. But what I worry hear is a higher vacuum tank pulling from another via the interconnections.

How bad do things get if you get backflow into your process/condensate lines feeding these tanks?

Bystander said:
How bad do things get if you get backflow into your process/condensate lines feeding these tanks?

Not very bad. It won't be a disaster if there's any intermittent cross contamination.

So long as, on average, in the long run I can stabilize the system without any inter-flows.

Hi,

Let's say I have an air compressor. If I compress exactly one kilogram of air at STP, I mean the total mass of the sealed tank is one kilogram plus the mass of the tank when empty, it will take a fixed amount of energy to do that. Now suppose my compressor is located at 1km up in the atmosphere. I also operate it to compress exactly one kilogram of air into the empty tank. My question is this; does it take exactly the same amount of energy to compress the same mass of air into the tank regardless of altitude or does the energy required to compress exactly one kilogram of air increase at an altitude of say 1km?

Or more simply put, does it take more energy to compress the same amount of air at altitude and if so, does that extra energy exactly correlate to the gravitational potential energy ?Thanks.

Last edited:
What stops the three source tanks trying to equalise their pressures?

## 1. How does a common pump work in pumping water from multiple tanks under vacuum?

A common pump, also known as a vacuum pump, works by creating a vacuum or low pressure in a closed system. This vacuum pressure then pulls the water from the multiple tanks into the pump through suction. The pump then pushes the water out through a discharge pipe to the desired location.

## 2. What are the advantages of using a common pump for pumping water from multiple tanks?

One advantage of using a common pump for this task is that it is a cost-effective solution. Instead of having multiple pumps for each tank, one common pump can be used to pump water from all tanks. Additionally, common pumps are also energy-efficient and can handle large volumes of water, making them suitable for this task.

## 3. Can a common pump handle different types of water from multiple tanks?

Yes, a common pump is designed to handle different types of water, including clean water, dirty water, and even chemical-laden water. However, it is essential to ensure that the pump is suitable for the specific type of water being pumped to avoid damage or inefficiency.

## 4. How often does a common pump need maintenance when used to pump water from multiple tanks under vacuum?

The frequency of maintenance for a common pump depends on various factors, such as the type of pump, the quality of water being pumped, and the frequency of use. It is recommended to follow the manufacturer's guidelines for maintenance, which may include regular cleaning and replacement of parts as needed.

## 5. Are there any safety precautions to consider when using a common pump to pump water from multiple tanks under vacuum?

Yes, safety precautions should always be taken when using any type of pump. It is important to ensure that the pump is properly installed and grounded to avoid electric shock. Also, the pump should be regularly checked for any leaks or damage, and proper safety gear should be worn when performing maintenance or repairs on the pump.

• General Engineering
Replies
4
Views
517
• General Engineering
Replies
50
Views
4K
• General Engineering
Replies
17
Views
2K
• General Engineering
Replies
6
Views
4K
• General Engineering
Replies
48
Views
9K
• Classical Physics
Replies
3
Views
837
• General Engineering
Replies
10
Views
10K
• General Engineering
Replies
4
Views
2K
• Mechanical Engineering
Replies
15
Views
2K
• General Engineering
Replies
8
Views
2K