How to use Wireless Pressure Gauge kit to flow test 

Attach the fire hydrant cap with valve and quick connect to a 2.5" hydrant outlet at the test hydrant (where you want to record static/residual pressure).

Open the sender case.  Slide the power switch to on.  The sender screen will display the working pressure range before switching to real time PSI display.

Close the case and latch it shut.  Using the quick connect, attach the sender unit to the hydrant cap. TIP: Hang the sender's lanyard around the hydrant control valve nut to let the sender dangle out of your way.

Open the bleed valve on the hydrant cap and open the hydrant control valve slowly to bleed air out. 

Once the air is out, close the bleed valve on the hydrant cap. You should now see static pressure on the sender screen.  Open the hydrant control valve fully.

Turn on your display unit if you haven't yet.  You can turn it on at any time during the process.  You should see the same PSI displayed on the display as is shown on the sender.

Then you head over to the flow hydrant.  You will test flow same as before using your preferred methods.

Before you start to flow water, long press the button to record static pressure, then double click it to advance it to the residual pressure recording spot so you're ready when its flowing.  

Open the flow hydrant to the desired GPM and take your flow reading the same as you always did.  Now look at your display to see the residual pressure and know when you have at least a 25% psi drop for a good test.  Another long press on the button and the residual pressure is saved for you.

Start closing the flow hydrant while watching the display.  It's sending pressure readings 4x/sec so you'll know if pressure is spiking and to slow down your closing speed.

Wrap up by closing the test hydrant and retrieving the sender unit.