Natural gas flow rate for gas boilers

Provide the flow meter manufacturer with your pressure and pipe diameter; the manufacturer has the calculation standards.

This is a bit difficult! In actual work, it’s more accurate to use a flow meter. Even if a formula is found, the error will be large.

Just choose a orifice plate and a differential pressure transmitter!

The data that can be easily obtained on-site for a gas boiler are usually the diameter and pressure of the natural gas pipeline. The diameter can be measured directly with a tape measure, and experienced personnel can immediately determine what size the pipe is； Pressure can certainly be read from a pressure gauge; in the absence of a pressure gauge, the pressure difference can also be measured using a hose filled with water at the pressure measurement points of the gas valve assembly. The gas flow rate is an important parameter during boiler commissioning; if there is a gas flow meter, it can be read directly, of course. What if the conditions are not met? I would like to ask the experts: based on your many years of experience, is it possible to estimate the maximum flow rate of natural gas using its pipe diameter and pressure? By using the maximum flow rate, it is possible to roughly determine whether the boiler’s gas consumption can match the output required by the boiler.

In the calculation formula for differential pressure flow meters, the mass flow rate is related to the throttling coefficient, the area of the throttling orifice, as well as density and the pressure difference across the orifice. If it's to calculate the maximum flow, it might work.

Only an approximate range can be estimated based on experience and flow rate; the exact value can only be determined by using a flow meter

In my opinion, simply put, this issue comes down to how to determine the flow rate. If the pipes in question were designed by a design institute, that means the gas delivery pipes are compatible with those designed for the boiler; in such cases, the flow rate can be found by referring to the economic flow rate values specified in the design documents, and these values are generally quite accurate. If there’s no message from the general manager, then I can provide it. But if this pipeline was added on a temporary basis, rather than being part of the original design. For example, if it is necessary to add various pipelines for some reason, and the manufacturer in question already has pipes of a certain specification on hand, then if those pipes are to be used directly, the flow rate cannot be determined based on the optimal flow velocity. The issue of flow rate then becomes an issue of pressure (as it was a decision made on the spot); as for whether your pipes can meet the furnace’s load requirements, it comes down to the pressure at the gas supply end and the issues related to the pipelines. If the pipe is too small, the flow rate increases and the resistance rises; if the pipe is too large, it results in material waste. Of course, the pipe diameter cannot be too small, because the gas flow velocity inside the pipe is not a value that can be infinitely large. For temporarily decided cases, generally speaking, the diameter being large or small is not too extreme; what’s important is for the person in question to determine whether the pressure conditions can be met. For reference only!

Given the natural gas pressure and pipe diameter, the only value missing to determine the flow rate is the velocity; the velocity of natural gas is taken as 10 to 15 meters per second

The flow rate can be determined by observing the changes in pressure at the pressure regulator at the front end of the burner. For our systems using 50-mm pipes, a pressure drop from 6 KPA to 4 KPA corresponds to a flow rate of 150 m3/h, while a pressure of 5 KPA results in a flow rate of around 60–70 m3/h.