When to used a Balance proportioning system and an In-line Balance proportioning system?
In-Line balanced pressure systems are used when wanting to protect multiple hazards (each with different flow demand) with only one system. It is also used when simultaneous operation of several systems is desired, all fed by a single foam pump or bladder tank.
But even a balance proportioning system where the proportioner is within the skid can do it as well. As long as I'm using different proportioner as per flow demand of the hazard.
Although balanced proportioning systems can be used for multiple systems, in line systems balanced proportioning systems tend to have a wider range. Also, when proportioning below the system's listed flow range, the foam solution will be at a higher concentration percentage (up to double) than within the flow range.
The I.L.B.P. system is usually used where there are a number of hazards remote from one another. A centralized foam system (foam pump (s) & concentrate tank) would be set in a convenient location and a foam concentrate line would supply multiple risers, each containing an I.L.B.P. module. For example a very large warehouse could have multiple risers in each corner, far enough apart to where a separate foam tank would be required for each bank of risers and be expensive. Under these circumstances the I.L.B.P. system makes financial sense, because there would be a common foam tank with foam pump (s), using less foam concentrate in storage, compared to multiple foam tanks. Keep in mind that the foam concentrate required to fill the line from the foam pump to the remote I.L.B.P. modules is "dead" and it could be a substantial amount.
While foam pump systems (either balanced pressure skid with one (1) or multiple ratio controllers or I.L.B.P. modules) will proportion (very) rich at low flows, there are Wide Range Proportioners available that will accurately proportion down to 25 - 50 gpm with bladder tanks or balanced pressure systems. These devices were specifically designed for use with bladder tanks and closed head foam/water sprinkler systems.
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