Buying a sewer jetter: more pressure or more liters?

08 June 2020
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You can ask yourself: do I need more  “cutting” power or do I need more “flushing” power? Or in other words:  do I need “pressure” (Bar) or do I need “flow” (lpm, liter per minute)?

When using a jetting unit with a good jetting nozzle which creates “thinner” waterjet streams , you will have more cutting power in order to cut out roots, pulverize hard grease and carve out hard settled dirt.

When using a good jetting nozzle which creates “wider” waterjet streams, you will have more flushing activity and more impact on cleaning the drainage system.

If the flow is adequate enough, the volume of the water will push and carry sand, mud, debris, rocks and greaselogs.

The flow you will need depends on the pipe diameter which has to be cleaned and whether or not you are required to flush the pipe clean, or if you just need to penetrate a blockage which will restore the flow in the pipe.

The lpm-to-pipediameter-ratio is a good guideline in choosing the flow. A rough estimation could be  15 - 20 lpm / 100 mm pipe diameter), when the pipe is in good condition and not heavily polluted, and when a normal cleaning job has to be done.

When there is a heavy blockage or if there is a lot of material and debris in the pipe, the ratio will be less.

This all means that there are two main questions which have to be answered:

  • What is the primary job of the jetting unit: flushing dirt, rock, debris, or cutting roots and grease?
  • What is the most common pipe sizes which has to be cleaned by the jeting unit


Please bear in mind that:

  • a jetting unit has always loss of pressure. Even with a good selected nozzle which is in good condition, you will loose approx. 15% of pressure. Pressure loss is a combination of the hose lenght and its diameter. The pressure loss will greater as the hose diameter decreases, and the length increases.
  • Only at full throttle, the jetting unit will reach the maximum flow. Flow is more important than pressure in larger pipes and smaller jetting units operate at higher pressure and lower flows in smaller lines.


“Cleaning points” is pressure multiplied by flow:
A jetting unit with 300B / 30 lpm (300 x 30 = 9000) has the same cleaning points as 150 B / 60 lpm (150 x 60 = 9000) or 200B / 45 lpm (200 x 45 = 9000).

The CompactPro Artic Version has 300 B / 30 lpm with a 3/8” HP hose and a SmarttrailerPro 150B / 60 lpm has ½” Hp hose.  The overall cleaning power though is better when using the SmarttrailerPor 150 B / 60 instead of the CompactPro Artic Version.

Many customers do make this mistake when they think that the unit with higher pressure will have a better performance. Only when customers  choose a higher pressure like 300B will make sense when they will use the jetting unit for de-icing pipes or cutting roots.

Nowadays with the high efficiency nozzles which are on the market usually 200 B will be suitable enough to do most of the “cutting” jobs.

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