tanker/tender tank construction

[Rescue101]

Chief,

Only because I have never had dealings with a vac tanker, what is the general price of a 3000 gallon unit on say an International chassis?

Quick quote pricing for us was in the $260 to 300k range depending on options. 4oo+ maxforce,allison 4000, 3500 water with a 500-750 pump and heavy rears.

[johnsb]

A rear "+" shaped 8" pipe with three valves would be the way I would want it setup. I would add a 3" vent the outlet to speed up the discharge rate. The other option would be a "T" with two 8" outlets with valves and 12 feet of hard plumbed discharge hose.

10" Newton dump valves will unload much faster.

[Rescue101]

And a vac faster than that.

[rmcatee1]

Appreciate the response chief. Like I said, I have zero experience with them and I didn't know what the ball park prices were.

[SuperFire123]

10" Newton dump valves will unload much faster.

Newton valves or similar would work well. With three outlets with individual valves it will allow more options depending on the drop tank location on-scene. Three other items to consider,How much time do the members have to practice driving/operating the unit,what type of roads will it be operated on, Size restrictions of the district response areas.

[Ranburne]

Would love to see a picture of the truck quoted on post 3. What was the price tag? Sounds about like what we are looking at. Over the years we have run just about all kinds of tankers. Most were home built until the last few years. If looking for water hauling only, I would go with eliptical tank with the ability to dump both sides and rear, which could be controlled from the cab. Makes for 1 man operation of truck, also keeps from having to have someone between the truck and the drop tank.

[johnsb]

Would love to see a picture of the truck quoted on post 3. What was the price tag? Sounds about like what we are looking at. Over the years we have run just about all kinds of tankers. Most were home built until the last few years. If looking for water hauling only, I would go with eliptical tank with the ability to dump both sides and rear, which could be controlled from the cab. Makes for 1 man operation of truck, also keeps from having to have someone between the truck and the drop tank.

Hopefully, we'll be getting updated drawings of that truck any day now. I'll try and post them here. The truck I described is a Pierce Impel chassis, price was just over $500K. Our theory in ordering our trucks it to try and have them overlap a bit so if one truck is down, we still have another that will fill that role. For example, this truck's role fits in between our 2000 gal dump tanker and our engine. This truck can operate as a 1 man operation or as a traditional engine company, and it can also operate as a water supply engine.

[simpleguy68]

Poly or S/S wrapped poly

For the same amount of water, round will be longer than oval, which is longer than T-shaped or square.

One thing to think about is per-axle weight. 2000 gallons on a single-axle actually has a higher per axle weight than a 3000 gallon on twins.

[Fyrtrks]

Well you can vary the length of the unit by varying the height of the tank/barrel. If you need a short OAL unit the tank can be higher. You have to remember the need to keep proper design in mind when working on shortening up your unit.

[kuh shise]

I have been thinking about posting on this subject ever since the O.P. started this thread.

I am fortunate to be exposed to numerous tankers (tenders) and a broad spectrum of Fire Departments from the affluent to the Hard Scrabble Rural volunteers. One thing that stands out in the usability area is a power to weight ratio that keeps the unit maneuverable while providing climbing and acceleration for use in mountainous terrain. I do not necessarily refer to long climbing distance, but even to pulling up out of river bottoms to reach good hard roads. Experience indicates that volumes of 2,000 to 3,000 gallons seem to be the most effective at both parameters. Tanks of over 3,000 gallons tie-up the dump site for excessive periods. The goal should be to stop, dump, and roll within 2 minutes, thus keeping the wheels turning most of the time. Weight placement with a tandem rear axle is critical in providing enough steer axle weight to allow tight turning without having the front push through the turns, especially in winter weather. Locking in a power divider will push the front end right across a two lane road when climbing up out of a stream access and turning onto the main highway.
Recent opportunities to work with and next to vacuum tankers at fill sites has shown the great advantages realized with these types of apparatus. There is still an advantage to having a large pumper with multiple suction sleeves in the water source, and a fill set-up where fill rates are consistently above 1200 gpm. (fill times significantly under 2 minutes) The vacuum tankers really shine where the distance from the tanker to the water source is over 30 feet horizontally. Conventional engines simply can’t move enough water over long distances and/or high lifts. With a good vac-truck operator, the tank is under vacuum before the empty truck reaches the draft point. Connecting the suction tube (6”) in the dry state is relatively easy, and the instantaneous application of vacuum to the line by opening the 6” valve makes the water literally fly into the tank at 1,000 gpm or more. DO NOT buy any tanker with less than two (2) – 3” gated fill lines. Keep the piping as short as possible, (10 in. or less) and the valve bodies at least 3” I.D.’s. Filling with 4 or 5 inch lines becomes a pain if the line can not be quickly bled empty to allow easy disconnecting of fill lines.
At the dump location, no one should be required to step between the tanker and the drop tank. Automatic air operated extensions and large dump valves will allow the driver to make the drop without exiting the cab. Side dumps will aid in reducing the number of back-up operations needed. Do not plan on backing unless there is no other way to access the drop tank. Dump rates of more than 1500 gpm should be the minimum acceptable rate.
Safe travel should be the paramount consideration when designing tankers. Stability and handling control are vital elements, as well as baffling to prevent surging and side sway. No one should be permitted to operate or ride in a tanker unless restrained with both lap and shoulder belt.
Unless the wheels are turning on the rig, no water is being moved to the scene. Speed will not replace rapid fill and dump times. Assuming an acceleration from 0 to 45 mph in 0.1 mi and the same deceleration rate, then the travel time for a fill and dump site separation of one (1) mile, we have a travel time of 200 seconds. If we allow our driver to run at 60 mph, the we can get the travel time down to 144 seconds or an average of 56 seconds quicker per trip, but at what loss in safety? Taking 30 seconds out of both the fill and dump times, we get the same effect with none of the risk. Since the physics controlling the forces on the apparatus are a square function, increasing the speed from 45 to 60 causes the risk to be almost doubled.

[johnsb]

]

Would love to see a picture of the truck quoted on post 3. What was the price tag? Sounds about like what we are looking at. Over the years we have run just about all kinds of tankers. Most were home built until the last few years. If looking for water hauling only, I would go with eliptical tank with the ability to dump both sides and rear, which could be controlled from the cab. Makes for 1 man operation of truck, also keeps from having to have someone between the truck and the drop tank.

This is an early drawing of the truck, we made a few mods to it. The biggest is going to a 3/4 height compartment on the officers's side giving us room for two compartments for hand tools over the rear axles. Most of the other changes are small, like eliminating the 2 1/2" intake on the rear since there was a large diameter one already there. I had to print the PDF file then scan it as a picture, so you may have to save the image to enlarge it to see the detail.