There are several options but to make a good decision here are a few things I think are important to consider when making the right choice.

TRAILER or SKID?

Since the last 20yrs more skids (machines to build inside or on top of a vehicle) are being sold. Main reasons: their advantages in the traffic, better protection against vandalism and weather and their price advantage.

TIP: You can of course build a skid into or on top of a trailer (double axle) but be aware that the weight distribution must remain well balanced.

If your rear overhang (space between axle and rear) is (too) long, there will be too much weight BEHIND of the axle causing not enough pressure on the tow coupling. => causing instability

In addition, the difference between driving with a full or empty water tank will make a big difference to weight distribution and thus driving stability.

MY ADVICE: skids should only be built into or on top of a vehicle. If you want a trailer, buy a whole trailer and not a skid!

POWER OF THE HP-PUMP

Before choosing the correct HP-pump here are a few things to take into consideration.

 PRESSURE & FLOW

Pressure is the speed of the water, with it you can remove the hard deposits

Flow is the flushing force of the water, with it you can drain (transport) the loosened dirt out of the pipe so that it will not cause a new blockage further down the pipe.

PRESSURE LOSS

The pump only pumps water, the pressure is built up by ‘squeezing’ the water jet.

So by using inserts with the right bore (the right orifice), calculated for the specific flow and pressure, the nozzle will build up to the correct pressure.

Imagine using the wrong HP-hose… a hose with a too small diameter for the flow of your HP pump…

The hose is already squeezing the flow, pressure is being build up inside the hose.

This is pressure loss (inside the hose).

Pressure loss can also arise within the machine itself (too small (cheap) use of components where the flow needs to pass and even inside the nozzle (some nozzles have a wrong design and cause 10-15 bar pressure loss)

Example or pressure drop inside the HP-hose:

HP-pump 200 Bar 70 lpm, 80m HP-hose DN12 (1/2”)

Pressure loss (pressure drop) is approx. 50 Bar. NET PRESSURE @ the nozzle 150 Bar.

HP-pump 200 Bar 60 lpm, 80m HP-hose DN12 (1/2”)

Pressure loss (pressure drop) is approx. 35 Bar. NET PRESSURE @ the nozzle 165 Bar.

HP-pump 200 Bar 50 lpm, 80m HP-hose DN12 (1/2”)

Pressure loss (pressure drop) is approx. 25 Bar. NET PRESSURE @ the nozzle 175 Bar.

REQUIRED FLOW

Normally house connections (4-6” pipes) require a minimum pump flow of 40-50 lpm

For larger pipe diameters the required flow is exponentially larger.

REQUIRED PRESSURE

More pressure is desirable as hard deposits can be cleaned better.

100-120 Bar (at the nozzle) is the minimum in order to be able to clean. For harder blockages (descaling) 175-200 Bar (at the nozzle) is required as a minimum.

REQUIRED CORRECT HP-HOSE

For house connections, the 1/2″ HP-hose is a good hose, but often customers are using a 3/8″ HP-hose instead. This smaller hose is a bit thinner and more flexible so it passes better through tight bends in the 3″ and 4″ pipes.

However, this smaller hose will have more pressure loss !

HP-pump 200 Bar 50 lpm, 80m HP-hose DN12 (1/2”)

Pressure loss (pressure drop) is approx. 25 Bar. NET PRESSURE @ the nozzle 175 Bar.

HP-pump 200 Bar 50 lpm, 80m HP-hose DN10 (3/8”)

Pressure loss (pressure drop) is approx. 95 Bar. NET PRESSURE @ the nozzle 105 Bar.

For main lines the small hoses are not suitable.

The flow is too small and there is a risk of the hose to get knotted inside the pipe !

DIAMETER OF THE PIPES

Let’s have a look at the standard scope of operations

What diameters of pipes does the customer come across most often?

• house connections (DN110/160-4”/6”)
• inside buildings (DN40-75-1,6”/3”)
• main lines/ street sewers (> DN200)

Some customers will reply:

Yeah but I also work in DN400….

The question is: what % of your time does this really happen? 1 time/week? 1 time/month?

If 80-90% of the time you are cleaning house connections (DN110-125) then a small pump with 40-50 lpm is sufficient. If you are cleaning mainly larger pipes a (much) stronger flow is recommended.

COMBINING IT ALL TOGETHER

Depending on the scope of operations we can advise the customer:

• advised flow rate
• advised pressure
• advised correct hose diameter

The above 3 parameters determine the choice of HP-pump and drive (engine)

EXTRA

Which other circumstances will effect the choice of the components?

LENGTHS OF THE PIPES TO BE CLEANED

Longer pipes require longer hoses.

This will effect the pressure drop !

MATERIAL INSIDE THE PIPES

Smaller pipes generally contain more blockages cause by FOG’s (Fat, Oil, Grease)

Larger pipes generally contain more sand and stones.

LARGER HP-PUMP

Larger HP-pump requires a larger engine to drive. The larger components have more weight so the machine will be larger which will require a larger truck/vehicle.

Larger pump flow requires a larger water tank too !

SERVICE

Any machine will sooner or later break down.

Service should be offered. When the machine is sold to a remote customer the service cannot be provided easily. Sometimes offering higher quality components is a better choice instead offering a low price.

The newly developed engines (KUBOTA) and options like remote control and other electronics require more and special service.

BUDGET

We all would like to drive a Mercedes but if the budget is too small we will have to make concessions.

NOZZLES

Many nozzles are available. A relatively small investment in nozzles increases the machine’s performance and thus pays for itself.

EFFICIENCY

If some of the above components are not well matching the efficiency drops down causing longer working times, more use of resources (water and fuel) and thus a higher cost of operations.