From the McMaster-Carr website I found the following information:

There are two main types of fire hose thread. NH (National Hose) , also known as NST (National Standard Thread) is the most common; it is not compatible with any other thread. NPSH (National Pipe Straight Hose) is also a popular choice; female NPSH threads are compatible with male NPT and NPSM (National Pipe Straight Mechanical) threads

They do sell an adapter that will go from NH/NST to NPT go to http://www.mcmaster.com/ and look for item number 6523T11. They also have various other sizes and combinations.

I have no affiliation with the above mentioned company other then a very satisfied customer. They typically only charge actual shipping costs with no handling fees. If it is in stock (it will tell you if it is) it ships within hours of placing your order. They seem to be unbelievably efficient.