Phone 346 262 6075 Mail


Fire extinguishing systems must be tested at regular intervals to ensure their functionality in case of a fire. This applies to the proportioner, with the correct proportioning rate being crucial. Find answers below to the questions asked most frequently about FireDos proportioner test operations.

Proportioning rate testing with FireDos foam proportioners

The proportioner's return line connection allows returning the foam agent to the foam agent tank under real operating conditions while measuring its flow rate. The foam agent flow rate and the extinguishing water quantity measured at the same time are used to calculate the proportioning rate without producing premix or foam.


  • How long does a proportioner test run take?
    Ideally, a test run takes less than 5 minutes.

  • Is really no foam agent injected, not even a little when switching the ball valve?
    No, if operated properly, no foam agent is injected at all.
  • How do I calculate the proportioning rate?
    The formula is:

    foam agent (l/min)
    ------------------------------------------ x 100 =  proportioning rate %
    [water + foam agent] (l/min)

  • How do I measure the foam agent quantity?
    Ideally, using a magnetic-inductive flow meter in the return line. Another way can be volumetric measuring in liters, using a vessel. The contained amount of foam agent can be passed back into the foam agent tank, preventing the consumption of foam agent even with this method. However, a pressure sustaining valve is recommended in both cases to simulate system backpressure.
  • How do I measure the amount of water?
    - using a separate testing line
    - using the measuring device for testing the fire water pump if the FireDos proportioner is installed near the fire water pump
    - using a flow meter in the supply line to the proportioner
    - using the water motor's number of revolutions
    - using the FireDos flow meter for the water motor
  • My measurement result deviates from the required proportioning rate, e.g. 3%. I have measured 3.3%. What next?
    The measured value is within the tolerance range. Proportioning is functioning optimally. The upper/lower limit for the nominal proportioning rate of 3% is at 3.0% to 3.9%. All values within this tolerance meet the proportioning rate's accuracy requirements.
  • What is the flow rate at which I should test my proportioner?
    Thanks to the option to return the foam agent without consuming any foam agent, all FireDos proportioners can be tested across the entire operating range – i.e., also at the maximum permitted flow rate or at the individual maximum operating range.
  • Can I re-adjust a FireDos proportioner on-site later on?
    No, a FireDos proportioner is a fixed unit consisting of a water motor and a pump, connected by a coupling. Also, the liquid volumes delivered by water motor and proportioning pump are fixed and fine-tuned to each other in such a way that they always provide the necessary ratio of foam agent and extinguishing water reliably to ensure the respective proportioning rate at the required precision. Any readjustment, later on, is neither possible nor necessary.
  • How often should I test the proportioning rate?
    The recommended testing interval is once per year. This also meets the requirements/recommendations by approval bodies such as VdS and FM Global.

More questions? We'll be happy to help!

this might also be of interest for you:

Stationary foam proportioners

Improve performance, save costs: Learn more about the advantages.

View more

Firefighting with foam

How to reduce the Total Cost of Ownership

View more

How does a foam proportioner work?

Watch this video to learn more about the working principle.

View more