Pump and Seal Reliability

Water Saving Numbers Explained

Posted by Chris Carmody on 10-May-2016 10:38:50


We have recently released a very high quality 19-minute free training video on sealing technologies & water saving.

Since we are publishing this training, I wanted to provide a little background on some of the numbers around the flush water consumption of packing and single mechanical seals.


How we calculated “95 Billion litres saved”

People are always surprised by the sheer volume of flush water consumed when they work it out over a year. Here is an example from a typical application:

When water consumption is measured for one minute, a typical value is around 12 liters per minute (3.17 gallons per minute). In continuous operation we multiply this by the 525,600 minutes (60 * 24 * 365) in a year. This flush amount results in 6.3 million liters or 1.7 million gallons of water consumption per year.

By retrofitting a water management system (which uses only 32 liters / 8.45 gallons per year) to each of these applications we are saving 6,307,168 liters / 1,666,178 gallons per year.

For the past 3 years we have supplied an average of 3,000 of these units per year, thus arriving at the total estimated saving of 95 Billion liters or 25 Billion gallons per year.

Important note: what does “consumed” water actually mean?

In this instance, water consumption refers to the volume of water either entering the product or leaking from the pump. Of course, in reality this water may sometimes be reused or reclaimed downstream.

There are too many possibilities for us to cover them all – but here are three common scenarios:

If clean water is used to quench the seal and then flows to effluent, all of this water will be charged to your plant with both a direct supply cost and an effluent disposal cost.

If the water is treated and recycled by an internal effluent-processing system, the total cost may be reduced. Please note – there is still a substantial cost to your plant in cleaning this water, and once treated it must still be pumped back around, etc.

If the water enters the product and then has to be removed via. evaporation – this is by far the most costly scenario due to huge energy use. (See below!)

Energy consumption

One of our engineers sent me a concise summary of indirect energy use. I have included this below. (Clearly this is a useful guide only. Your local sales engineer can use our software suite tool to produce a specific estimate with ROI).

If you flush a stuffing box with 1 million US gallons a year that is 8 million pounds of water.

If the flush water temperature was 40°F and the process is 100°F, the added flush water has to be heated by 60°F (process is usually in excess of 200°F).

1 BTU is the energy required to raise 1 pound of water 1°F.

= 480 BTU’s are required to raise 1 US gallon of water by 60 deg F (8 lbs x 60 deg)

=  480,000,000 BTU’s are therefore required to raise 1 million US gals 60 deg F (BTU/gal x qty)

This means an application using 6 million US gals of flush water would require 2,880,000,000 BTU’s or 843,840 kW. At $0.05 / kW that’s $42,192.00 per pump per year.

Specific values will vary – but the important thing is the concept: there is a HUGE cost-saving opportunity in some applications by looking at the total cost. This is often overlooked because it falls between functional departments: maintenance/engineering don’t operationally monitor things like effluent costs and indirect energy bills. And environmental officers or general management rarely understand the intricacies of the mechanical seals and systems.

For anyone faced with specifying these systems, this advice might be helpful:

There is a lot of information available from us. As well as the 19 minute overview training check out the..

Seal technology training

this includes case histories, interactive content, and PowerPoint decks to help you sell this internally.

This is a maintenance/engineering/reliability issue. This is also an environmental issue. Talk to both teams! We’ve heard of several examples where these upgrades have been covered from an environmental/CSR budget.

I’ve mentioned it already – but the software suite contains a tool which allows your local AESSEAL rep to work with you to create a full ROI calculation. 

Topics: Fluid Management Systems

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