It sounds like you have ball valve issolator either side of your pump.
These are open when the screw slot is in line with the pipework. To close these valves the screw slot should be exactly 90 degrees to the pipe run.
Caution, I have seen some pumps with what appear to be ball valves, but are in fact not what they seem. So take care when you start to remove the pump, and be ready to retighten the gland nuts if there is an excessive flow of water.
With the slot inline with the pipe - is on - across the pipe is off. So quarter turn.
These valves are prone to leak, especially the older ones. If it has the option of using an allen key to turn - then use an allen key as you don't need to apply pressure. Using a screwdriver requires pressure to be applied and this causes the valve to leak.
Don't attempt to change the pump if you strapped for time, make sure you have time to drain down and replace valves if necessary.
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