Technical Feature
Jetter efficiency How to get a quart from a pint pot!
The demand for compact, lightweight van packs is increasing. Alistair Hiscock, Sales Director at drain jetter manufacturer Flowplant, examines this trend and its implications on jetter productivity.
Van mounted jetting units are very popular with drain cleaning contractors as, protected from the weather in the back of a van, they look better for longer and they’re easier to manoeuvre than similar trailer units. However, most fleet operators don’t want to run a vehicle with a gross weight of more than 3500 kgs because of tachograph and operator licence laws. Vans are getting heavier with the addition of goodies like ABS and emission compliant engines, and this means there is less payload available for work equipment.
Because the jetting unit is seen as the heaviest single item in the van, manufacturers have had to carefully review machinery design. Less metalwork or exotic alloys have helped and plastic water tanks weigh less than their metal predecessors, but more weight savings are still pushed for.
As far as a jetting unit is concerned, two factors rank most highly on the list of must dos. First, it has to pull a long way up the pipe and, secondly, it must have enough power at the jet head to clean effectively when it arrives at the blockage. Get both of these things right and productivity improves dramatically meaning more drains cleaned quicker and to a better standard. Squeezing the most out of these smaller units is therefore more important than ever.
But with less power to start with how can jetter productivity be maintained?
The answer is improved efficiency. Wasting less power getting water from the pump to the nozzle and then converting this power into usable cleaning energy is critical. A well designed jetter will minimise the pressure wasted between the pump and the main jetting hose. Pump hoses must be large enough to handle the maximum flow and control valves must be well designed and have sufficient bore size. Any hose, valve or rotary joint handling the main flow of the pump through a port of less than ½” diameter could be reducing the nozzle pressure by hundreds of psi. Obviously drain cleaning contractors have limited control over such matters but they can check
carefully when selecting a new machine and choose from a manufacturer that can demonstrate they understand and seek to minimise these wasteful losses through good design.
But an area where the end user can have a significant effect on the pressure reaching the nozzle is through their choice of main jetting hose. Take the following common example. A 54 l/min (12 gpm) jetter is fitted with 90m of 3/8” main hose and a 6m mini jet kit. If the jetter has a maximum working pressure of 200 bar (3000 psi), this hose combination soaks up more than 80% of the pump power just getting the water through to the end of the hose. That leaves only 35 bar (500 psi) at the nozzle - not enough to clean efficiently.
Alistair Hiscock, Sales Director, Flowplant
High efficiency jet nozzle
Tuffskin hose 10 drain TRADER | September 2015 |
www.draintraderltd.com
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