Australian Standards Covering Hydrant Pumps and Systems
There are many factors to consider when choosing a fire hydrant pump.
Here we take a look at the top two:
Know the System Pressure
One of the most critical considerations is system pressure. System pressure is the pressure at which water leaves the pump. Australian Standard 2419.1-2005 Fire Hydrant Installations nominates the minimum unassisted residual pressure required at the feed fire hydrant. In NSW, this is currently 150kPa for each fire hydrant required to flow at not less than 10 l/s. In all other states and territories this value is 200 kPa.
The system should be sized so that there is enough excess capacity to allow for fluctuations in demand and in flow caused by friction losses in the system. The total length of pipe between the main and each hydrant should also be considered in sizing the system. The system pressure will also determine whether you need a booster pump or not. A booster pump increases system pressure so that water can reach upper stories of buildings and higher places if necessary. Booster pumps are required for elevated buildings higher the 25 metres or buildings with pressurized water systems.
Consider the Motor Size
The other is motor size is affected by the capacity of the system it will be used with. It will also determine how much water can be pumped per second. The capacity of a hydrant system is measured by the amount of water it can hold at a certain pressure. If the system pressure is high, your fire hydrant pump must be able to handle it. The higher the pressure, the larger the motor size you need to get the flow rate you want. If your system pressure is low, you can use a smaller motor or one that has a lower flow rate. The flow rate of your fire hydrant pump is another important consideration. The higher the flow rate, the higher capacity pump you will need. For example, if you are looking for a fire hydrant pump, capable of a flow of at least 10l/s then your options are limited because not many systems can handle that flow rate with a good safety margin. Finally, we must remember that we also need to consider motor size when choosing our fire hydrant pump. The larger it is, the more power it will have and the higher capacity pump it can handle.
The size and power of a motor are determined by its voltage and current draw. Voltage is measured in amps, while current draw is measured in amps at 120 volts or amps at 240 volts. If you have an existing hydrant system, you will want to check your pump’s voltage and current draw so you can compare it to the specs of other pumps on the market.
Motor sizes usually vary from 1/3 to 2 horsepower. Most fire hydrants can be pumped with a 1/3 to 1 horsepower motor. If you have an unusually large amount of water to pump, you may need a 2 horsepower motor. The next thing to consider is the amount of time the pump will be used.
One way to determine this is to estimate how long it takes to fill a swimming pool. If it takes just over an hour, then a 1/3 horsepower motor will work just fine. If it takes longer than that, then a larger motor will be necessary.
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