How do I measure GPM Discharged from an Automatic Firefighting Nozzle?
What is an Automatic Nozzle?
An automatic firefighting nozzle is a variable flow, constant pressure nozzle capable of building a set amount of pressure within its flow range. The nozzle does this with a spring-loaded baffle that automatically alters the opening size at the exit of the nozzle. This allows it to build the appropriate pressure based on your flow.
How do You Measure GPM from an Automatic?
The easiest way to measure your GPM from an automatic nozzle is to use a water flow meter. Flow meters allow you to see flow rate in real time with your specific setup.
If you do not have a flow meter, you can use the PDP equation: PDP = NP+FL.