No matter what pump you choose or what type of apparatus you choose to have built, the intake and discharge manifolds, piping, and valves will affect operational performance.

National Fire Protection Association (NFPA) 1901, Standard for Automotive Fire Apparatus, and NFPA 1906, Standard for Wildland Fire Apparatus, only go so far and do not always provide the maximum performance possible from the pump and drive system selected.

1 This is a 5,250-gpm NFPA 1901 rated pump installed on a 600-hp custom pumper being tested using four sets of eight-inch suction hose. (Photos by author.)

Obtaining the maximum available performance is critical on high-flow applications such as industrial or other large property fires but is also important at the extreme opposite end of the market on slip-style wildland/grass apparatus where the engine driving the pump is very small, without the extra power to overcome the losses in the plumbing.

The current NFPA standards reflect historical conditions, situations, and technologies and at best reflect the commonly used state-of the-art technologies. This safely covers most apparatus being built but may not always provide the optimum performance opportunities available from the pump and engine selected. This is the first of two articles that look at intake and discharge systems on most types of fire apparatus. They will look at the current standards, current practices, and what would work better for many fire departments to optimize performance.

Performance Limitations

Intake performance when drafting is limited to the atmospheric pressure available to push the water into the pump. Losses in the suction hose and intake manifold system consume some of that atmospheric pressure. The lower the losses, the more performance can be derived from the pump. When you consider that atmospheric pressure can be no more than 14.7 pounds per square inch (psi), even small losses make a big difference. Even when pumping from a pressurized source, losses in the intake hose and manifolds are robbing potential performance.

The suction intake systems, as we know them, are based on using the smallest possible suction hose to get the minimum performance. Why? Because we used hard black rubber, very heavy suction hose for decades, and 4½-inch hose was much lighter than a five-inch let alone six-inch suction hose. Today we have lightweight hose and couplings that are easy to handle and deploy. The hose also bends better for easier setup. So, the size hoses we are used to for a given size pump could be looked at in a different light. Even eight-inch modern hose is easier to handle than the old six-inch, black, hard suction we used for decades.

As a pump designer, I look at the velocity of the water traveling in the pipe, waterway, or hose as a reference point in any evaluation of this type. The water speed is commonly measured in feet per second. To calculate this, I use the following formula: Velocity in feet/second = [0.32 x gallons per minute (gpm)]/the area of the waterway in square inches.

Further study of pump and system design books and various industrial standards reveals that 12 feet per second is hydraulically the ideal maximum design speed in an intake waterway/hose system. So, let’s look at what is commonly pur

No matter what pump you choose or what type of apparatus you choose to have built, the intake and discharge manifolds, piping, and valves will affect operational performance.

National Fire Protection Association (NFPA) 1901, Standard for Automotive Fire Apparatus, and NFPA 1906, Standard for Wildland Fire Apparatus, only go so far and do not always provide the maximum performance possible from the pump and drive system selected.

1 This is a 5,250-gpm NFPA 1901 rated pump installed on a 600-hp custom pumper being tested using four sets of eight-inch suction hose. (Photos by author.)

Obtaining the maximum available performance is critical on high-flow applications such as industrial or other large property fires but is also important at the extreme opposite end of the market on slip-style wildland/grass apparatus where the engine driving the pump is very small, without the extra power to overcome the losses in the plumbing.

The current NFPA standards reflect historical conditions, situations, and technologies and at best reflect the commonly used state-of the-art technologies. This safely covers most apparatus being built but may not always provide the optimum performance opportunities available from the pump and engine selected. This is the first of two articles that look at intake and discharge systems on most types of fire apparatus. They will look at the current standards, current practices, and what would work better for many fire departments to optimize performance.

Performance Limitations

Intake performance when drafting is limited to the atmospheric pressure available to push the water into the pump. Losses in the suction hose and intake manifold system consume some of that atmospheric pressure. The lower the losses, the more performance can be derived from the pump. When you consider that atmospheric pressure can be no more than 14.7 pounds per square inch (psi), even small losses make a big difference. Even when pumping from a pressurized source, losses in the intake hose and manifolds are robbing potential performance.

The suction intake systems, as we know them, are based on using the smallest possible suction hose to get the minimum performance. Why? Because we used hard black rubber, very heavy suction hose for decades, and 4½-inch hose was much lighter than a five-inch let alone six-inch suction hose. Today we have lightweight hose and couplings that are easy to handle and deploy. The hose also bends better for easier setup. So, the size hoses we are used to for a given size pump could be looked at in a different light. Even eight-inch modern hose is easier to handle than the old six-inch, black, hard suction we used for decades.

As a pump designer, I look at the velocity of the water traveling in the pipe, waterway, or hose as a reference point in any evaluation of this type. The water speed is commonly measured in feet per second. To calculate this, I use the following formula: Velocity in feet/second = [0.32 x gallons per minute (gpm)]/the area of the waterway in square inches.

Further study of pump and system design books and various industrial standards reveals that 12 feet per second is hydraulically the ideal maximum design speed in an intake waterway/hose system. So, let’s look at what is commonly pur

On May 29, 1953, Sir Edmond Hillary climbed Mount Everest, and when he stood at the top by himself, we all thought, “Wow! He is amazing!” But, what we didn’t see or hear was that he thanked the people who made his weatherproof boots that kept his feet from frostbite.

He thanked those who made his ropes that he hung his life on to get to the top. He thanked the people who carried all his gear and food to the final ascent.

Behind everything you do or use, there are people who should never be forgotten. They should never be disrespected, disregarded, or disassociated from the job we do, because if it wasn’t for them, you would not accomplish your job. They are truly your “guardians.”

In the fire service, we place our trust and confidence in the rigs we drive every time we hit the streets. We count on them to perform when we turn them on. We take for granted how this happens. Behind the scenes, there is always someone or a team who cares enough about our safety and the quality of our rigs to make sure they start, run, pump, and get us back to the station 24/7. We don’t send thank-you cards, though, do we? They don’t expect them either. They do it for the same reason you do your job-because they have pride in the work they do for you.

So, who are these dedicated individuals or “guardians of your fleet”? The days of the dreaded brake fade are gone. The new recruits may never experience the dreaded brake fade that happened with old drum brakes that put your heart in your throat when you hit the pedal and a red light was just ahead. Brake fade is almost obsolete these days.

How about pump packing failures, split-shift rear ends grinding, and fuses blowing that would all be remedied by a small adjustment or by a piece of cigarette pack tin foil and off we go again? We did it because we took a personal interest in our rigs. We did it so no one else had to bear the work load. We did it so we did not have to do without our rig for a minute or have to do a changeover to a less desirable rig. Our motto was, “Drive it like you own it, not like you rented it.”

How about if the rig ran rough? We would look at filing and resetting the points in the distributor and pull the spark plugs and run them over a wire wheel to give them another few months of life. A little file job and regap of the electrode and back in service it went. We shared in the ownership of our rigs that the mechanics tried to keep 100 percent fit.

I think we were all mechanics to some degree back then. Why? Because we grew up the same way. It was a different time. We never had the expectation that someone else would fix it. Nothing was thrown away. It was fixed.

Take a moment and reflect on the past. Imagine if you owned numerous cars and tried to keep all of them on the road running problem-free. Good luck.

Where have we evolved to in the 21st century? New cab safety and comfort have changed. Rig size has increased. Speeds have increased. Stopping distances have decreased with four-wheel disc brakes. We have air ride suspensions, air ride cabs. complete cab air bag systems, roll-over protection, LED lighting, touch pad pump panels, multiplex systems, electronic governors, and very large aerial devices.

We need to seek a balance in the fire service between what manufacturers can supply and what training our mechanics receive to repair these technological changes. Is your department taking proper steps to have your fleet guardians trained to diagnose and repair these rigs we use to carry out our mission? The equation is the sum of all the parts.

TERRY STEWART has been an active member of the fire

On May 29, 1953, Sir Edmond Hillary climbed Mount Everest, and when he stood at the top by himself, we all thought, “Wow! He is amazing!” But, what we didn’t see or hear was that he thanked the people who made his weatherproof boots that kept his feet from frostbite.

He thanked those who made his ropes that he hung his life on to get to the top. He thanked the people who carried all his gear and food to the final ascent.

Behind everything you do or use, there are people who should never be forgotten. They should never be disrespected, disregarded, or disassociated from the job we do, because if it wasn’t for them, you would not accomplish your job. They are truly your “guardians.”

In the fire service, we place our trust and confidence in the rigs we drive every time we hit the streets. We count on them to perform when we turn them on. We take for granted how this happens. Behind the scenes, there is always someone or a team who cares enough about our safety and the quality of our rigs to make sure they start, run, pump, and get us back to the station 24/7. We don’t send thank-you cards, though, do we? They don’t expect them either. They do it for the same reason you do your job-because they have pride in the work they do for you.

So, who are these dedicated individuals or “guardians of your fleet”? The days of the dreaded brake fade are gone. The new recruits may never experience the dreaded brake fade that happened with old drum brakes that put your heart in your throat when you hit the pedal and a red light was just ahead. Brake fade is almost obsolete these days.

How about pump packing failures, split-shift rear ends grinding, and fuses blowing that would all be remedied by a small adjustment or by a piece of cigarette pack tin foil and off we go again? We did it because we took a personal interest in our rigs. We did it so no one else had to bear the work load. We did it so we did not have to do without our rig for a minute or have to do a changeover to a less desirable rig. Our motto was, “Drive it like you own it, not like you rented it.”

How about if the rig ran rough? We would look at filing and resetting the points in the distributor and pull the spark plugs and run them over a wire wheel to give them another few months of life. A little file job and regap of the electrode and back in service it went. We shared in the ownership of our rigs that the mechanics tried to keep 100 percent fit.

I think we were all mechanics to some degree back then. Why? Because we grew up the same way. It was a different time. We never had the expectation that someone else would fix it. Nothing was thrown away. It was fixed.

Take a moment and reflect on the past. Imagine if you owned numerous cars and tried to keep all of them on the road running problem-free. Good luck.

Where have we evolved to in the 21st century? New cab safety and comfort have changed. Rig size has increased. Speeds have increased. Stopping distances have decreased with four-wheel disc brakes. We have air ride suspensions, air ride cabs. complete cab air bag systems, roll-over protection, LED lighting, touch pad pump panels, multiplex systems, electronic governors, and very large aerial devices.

We need to seek a balance in the fire service between what manufacturers can supply and what training our mechanics receive to repair these technological changes. Is your department taking proper steps to have your fleet guardians trained to diagnose and repair these rigs we use to carry out our mission? The equation is the sum of all the parts.

TERRY STEWART has been an active member of the fire

On May 29, 1953, Sir Edmond Hillary climbed Mount Everest, and when he stood at the top by himself, we all thought, “Wow! He is amazing!” But, what we didn’t see or hear was that he thanked the people who made his weatherproof boots that kept his feet from frostbite.

He thanked those who made his ropes that he hung his life on to get to the top. He thanked the people who carried all his gear and food to the final ascent.

Behind everything you do or use, there are people who should never be forgotten. They should never be disrespected, disregarded, or disassociated from the job we do, because if it wasn’t for them, you would not accomplish your job. They are truly your “guardians.”

In the fire service, we place our trust and confidence in the rigs we drive every time we hit the streets. We count on them to perform when we turn them on. We take for granted how this happens. Behind the scenes, there is always someone or a team who cares enough about our safety and the quality of our rigs to make sure they start, run, pump, and get us back to the station 24/7. We don’t send thank-you cards, though, do we? They don’t expect them either. They do it for the same reason you do your job-because they have pride in the work they do for you.

So, who are these dedicated individuals or “guardians of your fleet”? The days of the dreaded brake fade are gone. The new recruits may never experience the dreaded brake fade that happened with old drum brakes that put your heart in your throat when you hit the pedal and a red light was just ahead. Brake fade is almost obsolete these days.

How about pump packing failures, split-shift rear ends grinding, and fuses blowing that would all be remedied by a small adjustment or by a piece of cigarette pack tin foil and off we go again? We did it because we took a personal interest in our rigs. We did it so no one else had to bear the work load. We did it so we did not have to do without our rig for a minute or have to do a changeover to a less desirable rig. Our motto was, “Drive it like you own it, not like you rented it.”

How about if the rig ran rough? We would look at filing and resetting the points in the distributor and pull the spark plugs and run them over a wire wheel to give them another few months of life. A little file job and regap of the electrode and back in service it went. We shared in the ownership of our rigs that the mechanics tried to keep 100 percent fit.

I think we were all mechanics to some degree back then. Why? Because we grew up the same way. It was a different time. We never had the expectation that someone else would fix it. Nothing was thrown away. It was fixed.

Take a moment and reflect on the past. Imagine if you owned numerous cars and tried to keep all of them on the road running problem-free. Good luck.

Where have we evolved to in the 21st century? New cab safety and comfort have changed. Rig size has increased. Speeds have increased. Stopping distances have decreased with four-wheel disc brakes. We have air ride suspensions, air ride cabs. complete cab air bag systems, roll-over protection, LED lighting, touch pad pump panels, multiplex systems, electronic governors, and very large aerial devices.

We need to seek a balance in the fire service between what manufacturers can supply and what training our mechanics receive to repair these technological changes. Is your department taking proper steps to have your fleet guardians trained to diagnose and repair these rigs we use to carry out our mission? The equation is the sum of all the parts.

TERRY STEWART has been an active member of the fire