Frequently Asked Questions

When it comes to fire prevention, you should have plenty of questions.
Let’s see if we can answer any of them here.

Hydrant Flow Testing

Group 3 Copy 3 Why should I use a Hose Monster over the hand-held pitot method?

A few reasons: The hand-held pitot requires perfect positioning where the pitot is half the orifice diameter away from discharge and the pitot tube is perpendicular to discharge. This is nearly impossible to hold by hand, which is why you will see a bouncing gauge needle and inaccurate readings. The hand-held pitot method requires you to guess the required coefficient depending on the shape of the hydrant nozzle. This is not always known. The hand-held pitot requires that the water is discharged out into the open. This method is a risk to safety and can also lead to property damage. The Little Hose Monster™ with the Pitotless Nozzle™ or the steel Hose Monster make it easy to take consistent and precise flow-rate measurements that are FM Approved.

Group 3 Copy 3 How much is the friction loss when I use a hose?

A hose causes friction loss, but it doesn’t matter in a fire flow test. A hydrant flow test evaluates the water supply to determine what flow rate will be available at 20 psi residual. A hydrant flow test requires three measurements: static pressure, residual pressure and test flow rate. The reading from the gauge cap on the test hydrant gives you static and residual pressures. The Pitotless Nozzle or Hose Monster gives you the test flow rate. The friction loss created in the hose results in lower test flow and, at the same time, greater residual pressure. This does not affect the predicted flow at 20 psi, as long as you’re getting sufficient drop from static to residual. NFPA 291 recommends a drop of at least 25%, while AWWA M17 requires a minimum drop of 10 psi.

Group 3 Copy 3 Previously we did hydrant fire flow tests using a hand-held pitot. Why are our discharge flows different?

The test flow rate will be less, but the residual pressure will also be higher. This will not adversely affect the flow test when calculating water supply. Remember, the test flow rate by itself doesn’t mean much. You also need to take into account static and residual pressures. The discharge flow rates are also influenced by whether you’re flowing from the pumper port or the nozzle port of the hydrant, the length of hose and the flow test device.

Group 3 Copy 3 Can we use the table found in NFPA 291 to determine the flow based on our reading of the gauge from the Hose Monster?

No. The table found in NFPA 291 is not the same as the Hose Monster flow chart. We provide appropriate flow charts with each Hose Monster or Pitotless Nozzle sold. Flow charts are also available on the Literature Rack of If you are taking hand-held pitot readings directly from a hydrant nozzle or pumper port, use NFPA Table 4.10.1 and apply the correct coefficient(s).

Group 3 Copy 3 Do I take into account the hydrant coefficient when calculating flow rate from the Hose Monster?

No. The flow rate is measured correctly at the Pitotless Nozzle or the Hose Monster and not affected by the flow characteristics of the hydrant nozzle or pumper port.

Group 3 Copy 3 Why should I use a Remote Reader?

Three good reasons. It enables you to take the pressure readings away from the flowing water, it keeps you dry, and it also encourages workers to remove and safely store the gauge after a flow test.

Group 3 Copy 3 Is the Hose Monster or Pitotless Nozzle NFPA compliant? NFPA 291 outlines its procedure using a hand-held pitot.

NFPA 291 is a recommended practice but not a requirement. We are not aware of a standard that requires a hand-held pitot. NFPA does not yet require Approved/Listed devices for flow-rate measurement in either hydrant flow testing or fire pump testing. Standards tend to shy away from requiring a particular product to be used.

Fire Pump Testing

Group 3 Copy 3 How many Hose Monsters do I need for my pump test?

Generally, pump testers plan on flowing a maximum of 500 GPM per hose. There are other variables to consider such as pump capacity and hose length. We created the interactive Pump Test Hose Calculator that estimates the number of hoses required for a specific pump test based on the pump ratings/capacity, water supply, job conditions, hose diameter/length and nozzle size.

Group 3 Copy 3 Why should I use the Monster Tester?

Without the Monster Tester — Fire pump tests using multiple hoses require one gauge for each Hose Monster. It requires one person to adjust the water flow and another to take individual readings. Communication between both persons is via hand signals, radio or shouting. Mistakes happen. With the Monster Tester — One gauge is needed to take accurate readings of individual pitots. The Monster Tester can be remotely located at the test header so that the person adjusting the water flow can watch the pressure change. Opening or closing the hose valve is like dialing in target pressure.

Group 3 Copy 3 Can the Little Hose Monster or regular Hose Monster be used on a rooftop standpipe test?

Yes. In fact, a rooftop standpipe test should not be conducted without a Hose Monster. A Hose Monster unit allows a rooftop flow test to be conducted any time of day because no water is dispersed over the side of the building. The Little Hose Monster with a 1 ¾" Pitotless Nozzle or the 2 ½" Hose Monster with an FM Nozzle Insert are often used. Either one is placed directly on the roof. The major difference between both options is that the Little Hose Monster and Pitotless Nozzle weigh only six pounds, whereas the Hose Monster weighs about 30 pounds.

Group 3 Copy 3 How many hoses does NFPA require to be used?

NFPA does not specify the number of hoses required to perform a pump test. NFPA 20 Table 4.26 provides a required number of hose valves and the minimum hose valve size (typically 2.5") for installation of pumps. However, the table does not require a specific number of hoses to be used during a flow test. Some AHJs misinterpret this as the number of hoses to be flowed in a pump test. It does not, and we’ve verified this with NFPA.

Group 3 Copy 3 What is the maximum hose length allowable?

NFPA does not have a requirement for minimum or maximum hose length.

Group 3 Copy 3 Does length of hose in a fire pump test affect the accuracy of the readings? What effect does friction loss have?

The accuracy of the readings is not affected by the hose length. The pump’s net pressure (discharge minus suction) takes into account the extra work needed to pump water through longer hose. In certain job conditions, hose lengths greater than 50 feet may be required to discharge the water away from the building or landscaping. In these cases, friction loss may overcome the pump’s ability to force enough water through the hoses. Additional hoses usually solve this problem. If the flow-rate per hose is low enough, a smaller nozzle size may be necessary.

Group 3 Copy 3 What effect does flowing uphill or downhill with the Hose Monster have?

As long as you achieve your required flow (100%, 150%), the pump’s net pressure (discharge minus suction) should not be affected. When flowing uphill, you might have to use either more hose lines or shorter hose due to the extra work the pump has to do.

Little Hose Monster

Group 3 Copy 3 How much does the Little Hose Monster weigh?

By itself, it weighs only 3 pounds. With the Pitotless Nozzle and gauge, it weighs just 6 pounds.

Group 3 Copy 3 Will it whip around because it is so light?

No. The weight is not what keeps it from whipping around. The thrust is cancelled by flowing water in two opposing directions.

Group 3 Copy 3 The Little Hose Monster looks quite small. Will it break when flowing at high pressures?

The Little Hose Monster has been tested in numerous water flow situations as well as special destruction testing. We found that injection-molded, glass-filled polypropylene is exceptionally durable and difficult to damage — even when we try! But if your Little Hose Monster becomes damaged within two years, we’ll replace it.

Group 3 Copy 3 When I use the Little Hose Monster, it slides or moves laterally. How do I stop it from moving?

Such movement can occur if the hose is twisted or curved, or if the Little Hose Monster is on an incline. Straighten the hose first and make sure it is not twisted. You can also use the Little Hose Monster Stabilizer as an anchoring base.

Group 3 Copy 3 When I stack the Little Hose Monsters three units high, the stack gets top-heavy and falls over. How do I solve this problem?

Use the Little Hose Monster Stabilizer (STK). It adds stability and keeps the stacked units upright during heavy water flow. It consists of a specially designed metal base and tie-downs.

Group 3 Copy 3 What about dechlorination? Can I still dechlorinate with the Little Hose Monster?

Absolutely. Simply connect the Dechlor Demon™ to the hydrant, in line with the hose and the Little Hose Monster.

Pitotless Nozzle

Group 3 Copy 3 Why should I use a Pitotless Nozzle?

Because there is no pitot, small rocks and other debris can pass harmlessly through the center of the nozzle. The same debris would likely damage a pitot if it were in use. Plus, the Pitotless Nozzle accurately measures internal pressure from the inside of the nozzle to determine the flow-rate.

Group 3 Copy 3 Is the Pitotless Nozzle accurate?

Yes. The Pitotless Nozzle was tested extensively in two different private hydraulics laboratories before being tested at the FM Approvals lab in Rhode Island. K-factors are known and consistent. In addition, FM Approvals conducts regular audits of our manufacturing facility.

Group 3 Copy 3 In what applications should the Pitotless Nozzle be used?

It is used in flow testing, pump testing or flushing. Use it with the Little Hose Monster, the 2 ½" Hose Monster or by connecting it directly to a hydrant nozzle or pump test header flowing openly to atmosphere. Call us if you are considering another application.

Group 3 Copy 3 What are the minimum and maximum flow-rates that can be measured?

Rates as low as 50 GPM and as high as 1400 GPM can be measured. The nozzle comes in four sizes: 1", 1 ⅛", 1 ¾" and 2".

Group 3 Copy 3 Can I connect the inlet of the Pitotless Nozzle to a test valve or hydrant nozzle, and then connect a hose to the outlet of the Pitotless Nozzle?

No. There is not enough air ventilation inside the hose, and the discharge will cause hose burn. The outlet of the Pitotless Nozzle must be open to atmosphere or connected to the Little Hose Monster or Hose Monster with built-in flow splitter. If anything else is connected to the outlet end of the Pitotless Nozzle, readings will be inaccurate.

Group 3 Copy 3 Why do I get a suction or negative pressure when using the Pitotless Nozzle directly on a pump test header?

It is usually caused by the presence of air turbulence inside the Pitotless Nozzle. This can happen while opening a valve during a flow condition. This condition can sometimes be corrected by opening the header valve all the way and controlling the pump test flow from the valve at the pump. If this method does not work, attach a Stream Shaper, elbow or nozzle extension to the test header valve first, then attach the Pitotless Nozzle on the outlet end.

Hose Monster

Group 3 Copy 3 How much does the 2½″ Hose Monster weigh? It must be heavy to keep from whipping around.

The 2 ½″ Hose Monster weighs 27 pounds, and the 4″ and 4 ½″ Hose Monsters each weigh 45 pounds. However, their weight is not what keeps them from whipping around. The thrust is cancelled by flowing water in two opposing directions. The Hose Monsters weigh as much as they do because of the durable material they are built with.

Group 3 Copy 3 How much water can I flow through the Hose Monster without damaging it?

A lot, probably more water than your system can provide! Water never has and never will damage the Hose Monster.

Group 3 Copy 3 Can I take flow readings by inserting a hand-held pitot in the vent hole on top of the Hose Monster?

We do not recommend this method. The vent hole was not designed for flow readings, and the accuracy of that method has not been verified.

Group 3 Copy 3 What are the maximum and minimum flow rates I can read from the Hose Monster?

Our equipment can test water flow rates as low as 48 GPM (1″ Pitotless Nozzle™) up to 2943 GPM (4″ Hose Monster). Call us or refer to flow charts to determine which equipment to select. The flow charts provided with the Hose Monsters and Pitotless Nozzles indicate the flow rates for which we have supporting laboratory test data.

Group 3 Copy 3 Why do I need an extra pitot when I get the 2½″ Hose Monster?

Sometimes a piece of debris hits the Hose Monster’s built-in pitot and damages it in the middle of a flow test or pump test. When this happens, you can change out the damaged pitot with the spare that you keep on hand. All you need is the Pitot Change-Out Kit (PCK) — or a ⅛″ hex wrench and magnet — and a few minutes. And be sure to save the old pitot! It can be rebuilt at the factory for far less than the cost of a new pitot. Contact us for a return authorization.

Group 3 Copy 3 Where is the pitot in the 4″ or 4½″ Hose Monster?

These Hose Monsters use an FM-Approved orifice plate, not a pitot. It is ideal for flushing operations because it is both accurate and durable. We have never had a complaint of the orifice plate being damaged from flushing debris.

Group 3 Copy 3 Can I thread the Hose Monster directly to the hydrant?

It is physically possible, but it shouldn’t be done. The primary benefit of the Hose Monster is realized by using a hose. It gets the flowing water away from the hydrant and into the street gutter, plus it neutralizes the turbulence when flowing close to the hydrant nozzle. It’s common to see a gauge needle bounce ±10 or more psi when measuring flow close to the hydrant.

Dechlor Demon

Group 3 Copy 3 Can the Dechlor Demon be used in fire flow testing and water main flushing operations?

Yes. That’s what it is designed for.

Group 3 Copy 3 What is the maximum and minimum flow-rate capacity of the Dechlor Demon?

The Dechlor Demon has the capacity to flow as much water as a Hose Monster — or more. The 2½″ model has demonstrated that it can dechlorinate flow rates as low as 100 GPM, which is the flow- rate to be expected from draining a chlorinated water tank.

Group 3 Copy 3 Is it necessary to use the Hose Monster with the Dechlor Demon?

At least 5 feet of hose is necessary to use on the discharge side of the Dechlor Demon to ensure sufficient mixing of the dechlorinating agent with the chlorinated water. The Hose Monster or Little Hose Monster is necessary to cancel the thrust at the end of the hose.

Group 3 Copy 3 What levels of chlorine can the Dechlor Demon dechlorinate?

It is designed to neutralize low concentrations of chlorine, such as those found in normal potable drinking water. It can also neutralize concentrations in super-chlorinated mains.

Group 3 Copy 3 What chemicals can be used in the tank?

VC Mini Tabs and Vita-D-Chlor (both vitamin C) and Bio-Neutralizer (sodium sulfite) are recommended. Other chemicals may be used, but check with us first.

Calculating Flow Rates

Group 3 Copy 3 How do I calculate flow rates?

If you are using a software program to calculate flow, you may need to input a coefficient or K-factor into the program to calculate flow rate. Using the coefficients will give relatively accurate results. Check results against our flow charts to verify calculations were done correctly. Our flow charts are calculated using K-factors derived from testing at FM Approvals.

If you need the Coefficients, please visit our Hydraulics & Engineering Information page in the Resources section.

Here are the equations used for calculating flow rates and predicting flow rates.

Computes a flow rate in GPM given a psi and a K-factor of the flow device.
Q = √P x K
Q = flow rate in GPM
P = velocity pressure in psi
K = K-factor of flow device

Computes a flow rate in GPM given a psi and coefficient of the flow device.
Q = 29.84 x √P x D² x C
Q = flow rate in GPM
P = velocity pressure in psi
D = orifice diameter in inches
C = coefficient of flow device

Computes the flow rate available at a specified residual pressure (a.k.a. Rated Capacity). The example below enables you to find the predicted flow rate at 20 psi residual pressure. Use this when fire flow testing hydrants.
QR = QF x (HR0.54 / HF0.54)
QR = Flow rate predicted at the desired residual pressure in GPM
QF = Total test flow rate measured during test in GPM (GPM measured from Hose Monster or Pitotless Nozzle)
HR = Pressure drop from static pressure to desired residual pressure (Static – 20 psi [if 20 psi is the desired residual pressure])
HF = Actual pressure drop measured during the test (Static – Actual Residual)

US Gallons per Minute x 3.785 = Liters per Minute
Liters per Minute x 0.264 = US Gallons per Minute
US Gallons per Minute x 0.1337 = Cubic Feet per Minute
Cubic Feet per Minute x 7.481 = US Gallons per Minute

US Gallons x 3.785 = Liters
Liters x 0.264 = US Gallons
US Gallons x 0.8327 = Imperial Gallons
Imperial Gallons x 1.201 = US Gallons
Cubic Feet x 7.48051945 = US Gallons
US Gallons x 0.1337 = Cubic Feet

psi x 0.0689 = Bars
Bars x 14.5038 = psi
psi x 6894.757 = Pascals
Pascals x 0.000145 = psi
Bars x 100,000 = Pascals
Pascals x 0.00001 = Bars

US Gallons of Water x 8.3454 = Pounds
Cubic Feet of Water x 62.42796 = Pounds

Meters x 3.2808 = Feet
Feet x 0.3048 = Meters


Group 3 Copy 3 Where can I find information about Hose Monster pricing?

You can download a copy of our most up-to-date price list here.

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2023 Price List

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