Technology and Security



Hydraulic Calculation and sprinkler DesignI would like to tell you a story about how I met Jack. It goes back to the early days of hydraulic piping distribution calculations for water to sprinkler heads – not much past slide rules and calculators. Back in the day when hydraulic calculations were conceptual mathematical models that were based on civil engineering for underground waterflow for hydrants and water systems. Sometimes very crude “if this/then that” art forms were applied to sprinklers. Not reflective of fire science today.

In 1980, personal computers were basically about 640K of memory, perhaps slightly more – an extra thousand or two. Even a hundred thousand extra could be costly.

Our office maintains a sample of a cache transfer module from a DEC PDP System used to test the ARPANET – predecessor of the Internet – from The University of Pennsylvania in 1983. It is 100K of memory and is the size of a large cutting board. These were from the days when sizes of mainframe computers were measured in thousands of square feet.

When I heard Jack Crowley was going to be at the SFPE Philadelphia-Delaware Valley Chapter comparing some of the other systems that were around at the time – I believe six in total – I was going to be there, see the comparison, and meet this Jack Crowley about whom I had heard so much.

Jack created such a great program. You have to understand how hard it is to take a simple set of friction loss calculations, derive the results by node, transform them into a useable configuration that could be input easily, and provide a representation that everyone can understand. It’s mathematically difficult due to the number of variables-differences.

US Fire Trends Chart

Fire Trends Chart

Jack thinks in large numbers. He’s able to put these numbers into great perspective. But he is truly a fire protection engineer. Graduating with the likes of Rolf Jensen and Schirmer from the same school a decade before, Jack should be recognized for his pioneering work. Because if wasn’t for Jack, many of the things that Jensen and Schirmer and all of us strived toward, protection of life and property, couldn’t occur without Jack’s fundamental use of great mathematics, applied to simple personal computation. In a large sense, many fire protection firms’ successes rode on the coattails of Jack’s methods, manipulations, and, more importantly, extraordinary validity of performance. If it wasn’t for the ability to calculate flows, correct densities, coverage, and adequacy of water supply through available system pressures into relatively miniscule orifice heads to throw distances of over 20 feet, lives would be lost, property ruined.

It is this fundamental solution that Jack brought to the world that has been used not thousands of times, but millions of times. It is fair to say that even if Jack has saved one life in this world, his invention is remarkable. But it is truly astounding to think that Jack’s invention, his engineering application of hydraulic sciences to real world data, may have saved thousands of people from fire. Here’s why:  From 1977 to 2016 there have been about 200,000 fire deaths, with a peak in 1978 of 7,710 deaths; 2012 saw a low of 2,855 even with a preponderance of synthetic man-made materials and a record of stored commodities in the most recent years which should have increased fire deaths. If it can be assumed that the use of sprinklers is somewhat proportional to the decline in fire deaths, and that Jack’s equations have had some relative impact on that number, then the sheer fact that the loss of life through fire has diminished rapidly over the past 40 years – in fact, in half – then we can infer that Jack’s inventiveness has saved many lives in the U.S. alone. And wrongly, one might assume that with the introduction of smoke detectors, sprinklers would become only property safety devices secondary to early warning devices.

I saw this opposite effect inaction in 1995. We were designers for a new 1,000-student high-rise constructed for Rutgers University and Robert Wood Johnson Hospital in New Brunswick, NJ. One month after occupancy, students were partying with lighted candles on speakers. The synthetic drapes instantly caught fire. If it were not for low pressure, extended throw, quick response head hydraulic calculations to verify adequacy, lives may have been lost while injuries surely would have occurred and I would not be celebrating my firm’s 30th anniversary. Not one injury; but a few wet kids.

Jack’s inventiveness of 1982, 34 years ago, remains the litmus test of hydraulic calculation and sprinkler design software in use today.

Jerry ‘Dutch’ Forstater, PE is CEO of PSE, a planning, design and project management firm with over 35+ years in security, fire protection, communications, and energy controlled environments. He brings continuity and world-class engineering to the data-rich security operations environment to improve operator dynamics, situational awareness, process control and mission effectiveness.

‘Dutch’ can be reached by phone (800) 839-5060 x107 or by email @

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