Hello Everyone,

Is there any standard for Fire Water monitors reaction force calculation or can anyone guide me how to calculate that please?

Thanks

If you're familiar with Bernoulli's equation, I recommend studying back on that, and assume your firewater system has no pressure losses.

If you're unfamiliar with Bernoulli's equation, you might want to ask an engineer for the calculation, or at least to walk you through it, or look up some videos to explain it.

Charlot,

Some manufacturers are giving you directly the reaction force, see for example:

https://smhttp-ssl-61500.nexcesscdn.net/...ore-nozzles.pdf

Now, because your question was " how to calculate". Regardless Mr. Bernoulli contribution to science, the theoretical nozzle reaction force is R=rho*Q*V=rho*Q^2/A where Q is the discharge flowrate. The Manufacturer lists the K-factor and Q=K*sqrt(p) but is not usual to list V or A.

As a nice theory published in Fire Technology, where you can even meet Mr. Bernoulli:
https://backend.orbit.dtu.dk/ws/portalfi...Technology_.pdf

Also a theoretical remark. Generally for a free jet, the theory is complicated by an additional term, pressure dependent which is not the upstream pressure neither the atmospheric pressure. It is the case of a sonic jet (that one in PSVs exit, for example) where the "wave" has also this contribution.
Obviously, it is not the case here, where it is assumed that the free liquid jet is actually a streamline along which the pressure is atmospheric. In brackets, this is not really accurate near the nozzle exit but for an engineer is way useless to consider this fact.