Associations, Engine Company, Fire Department

Linking Two or More Tanks Together

Issue 8 and Volume 11.

Get two siphons and then you can link three portable tanks together. You’ll quickly wonder how you’ve gotten along without them all these years.

The practice of linking two portable tanks together isn’t a new idea, nor is the concept of power siphon adapters. For decades, fire departments have used what many firefighters call “inchworms.” Those are 4- or 6-inch PVC pipes and elbows fashioned to create an up and over effect to hydraulically link two or more tanks together.

The biggest problem with inchworms is they rely solely on gravity and the physics of siphoning to transfer water from one tank to the other. They often loose prime, especially when the water levels in the portable tanks vary widely – an inevitable reality during tanker shuttle operations. On a cold night in winter, in any part of the country, you don’t want to be the one to reach into the Fol-Da-Tank to reestablish the inchworm siphon.

There is a better way.

The power jet siphon allows the transfer of water from one portable tank to another with the assistance of a 1.5-inch line that creates venturi action which is far more reliable than a simple inchworm siphon. And, a lot more water can be transferred quickly with a power siphon.

Power siphons are simple devices that thread into hard suction hose and, depending on the manufacturer, have a three-point stand off with a female coupler into which a 1.5-inch hose is threaded. Others simply have a ring of male thread on to which a pipe with a 90-degree angle is bent and centered in the ring on one end and with a female 1.5-inch coupler on the other.

Power siphons are made by Kochek, Red Head, Action Coupling & Equipment and others. The price ranges from under $100 to more than $200 depending on the size and the design. Some can run much higher, depending on the applications.

Keep in mind they’re all designed to do the same thing – create a venturi to move water. They work particularly well with the flexible suction lines offered by Kochek and most recently TFT. The flex suctions are good for this operation as they’ll bend into the portable tanks and are much easier to handle.

And, as a quick refresher, a venturi increases fluid’s velocity, while decreasing the fluid’s pressure through a constriction. By placing a tube or pipe at the constriction point creates a vacuum which draws the fluid through the tube.

Establishing the power jet siphon flow is as easy as cracking open a discharge valve. At low discharge levels, say 50 psi on the inch and half, or less, you’ll get a one-way flow from one portable tank to another at an impressive rate, not quiet the same as a 10-inch dump valve can discharge, but enough to equalize portable tanks and keep a steady flow of water to your supply line. You’ll have to practice at how much 1.5-inch discharge pressure works best for you. Varying the discharge pressure to the siphon will also allow the pump operator to vary the speed in which water is transferred. Make sure you tie the suction hoses down as they will tend to walk and shift the more pressure you put to them. And don’t worry about pressurizing the hard suction in this application as you won’t be putting enough pressure to cause any damage. In most cases, pressurizing your suction hose is a big no-no.

The beauty of this arrangement is the water keeps circulating in the pump to prevent freezing in the winter and to prevent the pump from overheating from re-circulating water just in the pump.

Three or more tanks set up work the same way, but you’ll need at least two power jet siphons and two available discharges. If you’re the supply engine, that shouldn’t be a problem because all you’re doing is keeping the large diameter hose (LDH) filled. So, the crosslays, the rear discharge, other disharges on the pump panel should be available. You can even use a gated wye to get more discharges.

It might get a little tricky to do if you’re the attack engine and you’ve got a number of hand lines off, but you should be able to find at least one unoccupied discharges. In reality, if you’re the attack engine pump operator, you shouldn’t have to worry about water supply issues anyway – at least not in the perfect world – as mutual aid crews should have automatic responsibilities for that.

A Thing Of Beauty

Having three full portable tanks on the ground, linked with power siphons and tankers backed up to each is a thing of beauty for the pump operator. Depending on the size of the portable tanks and the size of tankers/tenders backed up waiting to discharge, you could be able to tell the incident commander that you’ve got 12,000 gallons or more waiting to be sent.

More realistically, the pump operator has been busy  getting as much water to the scene while trying to set up the multiple power jet siphon operation. It’s not something the pump operator can do single handedly. It will take some staffing to pull it off in a timely fashion and for it to actually have an effect on the suppression operations.

Too Much Too Late

You don’t want to have too much too late. It’s embarrassing finally have the operation in place and running, only to have the incident commander say overhaul is underway and you can start breaking down. It will be almost as hard finding a place to off load that 6,000 gallons in the portable tanks as it was getting it in there in the first place.

Some thing to remember when setting up more than one portable tank is positioning. It takes a lot of room to set up three 2,000-gallon tanks. Keep in mind the tanker drivers are going to have to maneuver and discharge their water in a safe and efficient manner so the more room the better.

Consider placing multiple portable tanks in diamond patterns point to point and points to the supply apparatus as well, if you have square tanks.

There are a number of advantages to this arrangement. First, it gives the pump operator a safety zone in the voids between the tanks. It also provides access to side compartments. That’s not an issue for apparatus with roll-up doors, but with standard cabinet doors, forget about getting anything out of the compartments with a portable tank mashed up against the side of the apparatus. Whatever’s in there is going to stay until the entire operation is over and the portable tanks are drained and stowed.

And, speaking of draining, don’t forget to locate the drainage chute on the down hill side of the scene to make it easier to get the water out of the portable tank when breaking down the operation. The same gravity that help drain the tank when operations have ceased is the same gravity that works against us while trying to drain to drain portable tanks with the chute pointing up the slope.

Chute placement can also be extremely important in the winter in cold regions. Draining a Porta-Tank on the roadway at minus 20 degrees is a recipe for disaster not only for motorists, but firefighter who must traverse the area during overhaul, salvage and pickup.

All of this might seem elementary, but it never hurts to have a brief refresher. Even the veteran can make an error without occasional refreshers.

Another advantage of placing portable tanks in a diamond is that it gives each tanker driver a target. And remember, it should be part of your standard operating guidelines to have a spotter backing all apparatus. In the heat of the battle, people get excited, accelerator pedals become confused with brake pedals and, without an extra set of eyes, disaster can happen in seconds. And, we can’t say this enough, never, ever, stand directly behind an apparatus backing up. The few seconds you might save jumping up there to grab the dump valve could cost your life.

Some departments have side dump valves and the diamond pattern works well with those too – in some cases better. The tanker/tender operator can select the tank to dump into because just driving along side will give them access to all the tanks set.

In those rare incidents where you actually have three tankers trying to back up to the tanks, it will be incumbent upon the water supply officer to make sure those operations are going smoothly. Remember, the pump operator’s mission is to keep that supply line full at all times and the operator is concentrating on moving water from one tank to another to maintain the highest flow possible into the one from which he’s drafting. The pump operator should not be expected to back up the apparatus and coordinate the tankers/tenders while running the supply engine.

Cooperation Needed

The pump operator and water supply officer should have an understanding that filling the empty or low portable tanks is more important than filling the one in which he is drafting, or filling the one that’s easiest to get to. The pump operator can easily fill the one from which he is drafting using the power jet siphons and the discharges, transferring water from the two on the outside into the middle one, for instance.

The old saying is that big fire requires big water. If your department is in the habit of throwing just one portable tank on the ground, think about all the advantages of having two or more down and linked. Try it and you’ll see the difference immediately. Some departments set down five, six or seven. As long as they’re all linked and you’ve got enough real estate and enough discharges, even if you have to use another pumper just to move water around in the portable tanks, you’re unlimited.

Many departments make it a practice to lay in LDH to a scene every time regardless of the fire load or the incident “just in case.” Those departments who rely on tanker shuttles ought to throw their portable tanks too and link them with jet siphons, “just in case.”

Just do it safely so everyone goes home.

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