Should You Invest in a Jet/Vac Combo?

Making the initial investment in a jetter/vacuum combination truck is a big decision. Tripp Amick, owner of A&H Equipment in Pennsylvania, shares some advice on what you should consider when buying or upgrading your equipment.

“Combination machines have grown in popularity because of their ability to offer a complete maintenance solution for both storm and sanitary sewer lines,” says Amick. “However, there are choices to be made when purchasing a unit. The type and size of the proper unit depends primarily on your application.”

Suction: Wet or Dry?

Amick: Combo machines come in two basic styles. “Fan” or “Centrifugal Compressor” units primarily use air movement to lift material and debris up the suction hose into the hopper while “PD” or “Positive Displacement Blowers” use a combination of air and “true vacuum”.

Fan units are most popular in straight catch basin cleaning as they handle drier materials well and don’t have the close tolerances found in PD blowers. However, if the debris is mostly liquid as found in sanitary lines, PD machines can be more efficient and can move the material greater distances, especially horizontally.

Fan machines are most typically “dual engine” units, utilizing both the chassis and an auxiliary engine to power the suction or the jetting functions. PD units mostly utilize the chassis engine for both functions. Therefore, chassis horsepower has to be considered when speccing out your unit.

What about Boom Hose Diameter?

Amick: Boom hose diameter on most full size combination units is 8″. Some smaller models will move down to 6″. It doesn’t sound like much of a difference, but it is! In fact, an 8″ hose has nearly twice the area as a 6″. This severely reduces both the amount of material that can travel up the hose and the size of the material you can suck up without clogging or blocking the hose.

Jetting: How Big, How Long and How Steep?

Amick: Most combination units are available with a variety of water pump options offering a range of pressure and flow choices. As a rule of thumb, the higher the pressure (PSI), the lower the flow (GPM) the pump will deliver.

Picking the proper combination depends on a bunch of factors.

What Size Pipes Are You Cleaning, and How Much Material is Usually in Them?

Amick: Larger pipes generally require more flow to be cleaned effectively both because of the greater diameter and the potential of more material. Pressure is responsible for loosening the material, but flow is what moves it down the pipe. Having the right combination will increase your productivity considerably.

How Far Do You Have to Jet from Manhole to Manhole?

Amick: The jetter has to have a large enough hose reel and water carrying capability to at least go this far. Most units come with at least 400′ and may be able to carry up to 800′ or more of hose. However, the more hose on the reel, the larger amount of “pressure drop” created by the friction and turbulence of moving the water through the hose. A pump delivering 2,500 psi at 80 GPM to 500′ of 1″ hose will lose about 1psi per foot, resulting in about 2,000 psi at the nozzle.

What Diameter Hose Should the Machine Use?

Amick: Sewer hose is bulky and sometimes hard to handle. Some manufacturers offer higher pressure (3-4,000 psi, lower volume pumps using ¾” hose as a more user-friendly option. However the pressure drop at 50 GPM is 2 psi/ft, meaning you’re still only getting 2,000 psi at the nozzle!

How Severe is the Grade of the Lines?

Amick: Steep lines can be difficult for nozzles to climb. Nozzle selection can be key, but the steeper the grade, the more you need to rely on flow. The higher the flow, the more thrust the Nozzle is capable of.

How Big and Powerful is Big and Powerful Enough?

Amick: What’s the right size unit to purchase? What size PD Blower or Fan do you need? Really the answer is determined by all of the answers above. Once you determine what your basic requirements are, unit selection starts to define itself.

There are a couple of more things to consider, such as the 80-10-5 rule and using industry resources.

What is the 80-10-5 Rule?

Amick: Purchase the unit that will do the best job on 80 percent of what you need it for, understanding that it will be less effective for 10 percent of the remaining work, and 5 percent will be either difficult or require a different unit to be rented or the work subcontracted. Spending the money to be able to perform even those rare tough jobs can cost you a lot up front and in the future in increased fuel and maintenance costs.

How Should They Use Industry Resources?

Amick: What are others in your area running? Usually there is a reason! Also, find a distributor with a good reputation, longevity in your area, and a good solid customer base. They’ll be happy to help you define what you need and support it after the sale.

Jetter/Vacuum Combination Manufacturers

There are a number of manufacturers for you to choose from: Aquatech, GapVax, Super Products, Vac-Con, and VACTOR. Each of the manufacturers have a variety of things that make their truck unique. Answering the above questions for yourself will help you to determine which is the right one for you and your business.

Story by Jennifer Taylor

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