PRODUCT INFO:

Natural Gas, 1/2" FPT Gas IN/OUT, 4-8" WC
MAXITROL RV47L-44-0007
For NIECO broiler series: 300, 400, 500, 600, 800, 900.

Attention:
NOTE: GAS PRESSURE REGULATORS WILL NOT TURN OFF THE FLOW OF GAS.
The pipe fittings for this regulator are based on NPT pipe threads - dimensions according ANSI/ASME B1.20.1 standards.
Install the regulator properly with gas flowing as indicated by the arrow on the casting.
*NOTE - Do not install the regulator too close to the heating equipment or use in very cold environment. Heat or cold can change the resistance of the spring inside the regulator.

How to find the correct pipe thread size

WARNING: The NPT thread size is NOT referring to the size of the thread itself!
The plumbing industry standard for the pipe sizes is NOT always as straightforward as measuring the pipe.
Measuring the pipe will often mislead you into choosing the wrong pipe size.
The "pipe thread size" is measured and based on the inside of the pipe.
A lot of people measured the thread / the opening for the thread / outside diameter of the pipe, and thought that was the thread size. It was WRONG.
The NPT thread is referring to the Interior Diameter of the pipe.