Before anyone sells you a new seal, find out how much water the present arrangement uses. Some flush water is doing essential work. Too little can damage the faces. Too much may be a cost in water, treatment and product dilution. The aim is to measure the duty, not simply close a valve.
Start with one pump. Record its tag, seal type and flush or support arrangement. Note whether the water enters the product, goes to a drain or returns to a system. Measure the flow with a site approved, calibrated inline flow meter, or a temporary clamp on ultrasonic meter on a straight, full water line, with the reading validated by a competent person. Record the flow in litres per minute while the pump is running normally. Do not assume a bucket or drain reading equals the supplied flush, or that taking such a reading is safe. Do not change the flow to take a reading.
Record the hours the pump runs in a normal day and over a normal production period, and whether the water still flows when the pump is off. Daily water use in litres is the flow in litres per minute multiplied by the minutes the water is actually flowing. Keep the readings for each pump separate before adding them. Record supply pressure and whether flow changes at startup, at different duty points or during cleaning.
Now put the water figure alongside reliability. When was the seal last changed? How many running hours were achieved between repairs? Log leaks, stops, labour, lost production, cleaning and wasted product. Note the fluid, solids, temperature, pressure, shaft speed and any periods when the pump runs short of liquid. A high water figure with repeated seal failures is a different problem from a stable seal that uses modest water.
Check what the water is there to do. A process flush, such as a Plan 32 external flush, supplies a clean liquid where the process is abrasive and can also cool or lubricate the faces. That is different from a quench or cooling flow on the atmospheric side, or a barrier or buffer support for a dual seal. Map where the water goes in and where it goes out. It may enter the product, go to drain or return to a system, and it may dilute the product. The flow needed depends on the seal, pump and duty. Never throttle a necessary flush. Before any change, check the seal vendor minimum flow and the plant safety requirements.
With a baseline, you can compare options. That might mean correcting a poorly set or blocked flush, addressing the process or pump problem that is damaging the seal, or assessing another seal and support arrangement. Ask for the proposed flow and the expected service interval in writing. Then judge both against your measured starting point and the real cost of another stoppage. The best result is one your own plant can verify.
Related: Why does the same mechanical seal keep failing on my pump? and Seal Troubleshooting Guide.