Working the Angles

Optimal hose fitting geometry can give you better suction and help hoses last longer

QUESTION:

I’ve recently noticed that on some vacuum trucks, the suction fitting coming out the back end is tilted down at about a 45-degree angle. My truck has the suction line fitting coming straight out the back head, parallel to the ground. What is the difference? Did someone simply goof on those trucks with the angled fitting or is there a reason for the fitting to be like that?

Barry Wallenberg

St. Paul, Minn.

ANSWER:

On a septic service truck, the downward angle on that type of suction line makes a lot of sense. And it’s true a lot of trucks have the straight, horizontal suction line coming off the tank. A little history is in order: In the beginning, building and designing a truck usually meant everything was straight, balanced and looked good. Like so many things, sometimes cosmetics get in the way of function.

But as the suction hose was hooked up to the horizontal fitting over and over, the hose eventually ripped near the fitting as gravity pulled the hose 90 degrees down to the ground. Another downside of the horizontal hook-up was that larger, chunky contents got stuck as the hose became pinched and narrowed at the 90-degree bend.

Consequently, many recent designs changed to match the function. With a downward angle, the suction hose now came out straight, with no stress on the hose. The hose didn’t make the 90-degree bend right at the fitting, but rather it made a gradual angle as it touched the ground. This is much less stressful on the hose and easier on the truck owner’s pocketbook. Longer lasting hoses save money. Take a look at the photograph to see an example of a truck like yours with the suction angled downward.

PORTABLE SANITATION TRUCKS

The suction line on a portable restroom service truck, if not installed correctly, can also bind and pinch the hose. Just as in the septic service truck, it’s important to arrange the suction so the hose doesn’t make any sharp bends. A hose forced to bend 90 degrees will wear out prematurely.

We find that a 90-degree bend in the suction system is often required, but we don’t let the hose handle the bending. Rather than letting the wear part do the work, many truck builders use a steel elbow to make the necessary 90-degree bend. The accompanying photo of this restroom service vehicle shows how a steel elbow allows the hose to hang neatly around the hose wrap. When the hose is rolled out for service, there is minimal stress put on the hose, which extends hose life.

This arrangement provides the most trouble-free service. Of course, if you happen to suck up something that’s too large, you’ll have problems. But it won’t be because of the connection between the hose and suction line. So whenever you’re having a truck built or purchasing a used one, try to make sure the suction hoses will have a clear, unfettered path to the tank. Everything, including the pump will run smoother, better and longer.

ERGONOMIC HOSE WRAP

While we’re on the subject of function over form, here is another feature to incorporate into your next truck:

Something as mundane as the placement of a hose wrap can make a big difference in the technician’s performance. The hose wrap should be easily accessible and as low as possible.

Some hose wraps are installed so high on the truck that the technician literally has to throw the hose up and hope it catches the wrap. This costs time and technicians working these trucks could suffer shoulder strain or more serious injury. And when the technician shouts in pain, that’s the sound of profits going down the drain.

A properly designed truck may not always look as pure and pristine as one would like, but it will function more efficiently over time. Design features that make the technician’s job easier should be built into the truck whenever possible. Remember, some basic choices made for better ergonomics and service performance add little or no additional cost to a new service vehicle.

Not everybody pumps the same way, so maybe your next truck might not look just like every other hauler’s vehicles. But if your trucks are designed specifically for the type of jobs you perform and the comfort of your technicians, you’ll have no regrets.



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