Downtime Eliminator Flexo printing

Welcome to my column where I will share best practices for Flexo Wash technology and common flexo challenges. I want to answer your real world questions, so be sure to send them to me at: and we will feature them in an upcoming column. As your partner, I look forward to handling all your issues as soon as possible and offer lessons learned.

Question: I can’t adjust the pressure on the HP pump regulator.


We get the occasional call here at the shop regarding the pressure setting that the high pressure rinse pump should be set at on an anilox roll/sleeve cleaning unit. The rinse pressure setting should be, at the minimum, set at 1500 PSI. Let’s take a look on what might be causing the issue.

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The rinse pressure setting number can vary for older (pre-2008), narrow web 120V units (like a FW Handy or FW991XL). While I’m not an electrician, the reason for the variance is due to the electrical run going to these older units. For a quick reference on the high pressure rinse setting, see below.

PSI Settings for High Pressure Rinse Pump:

Pre 2008 120 V narrow web units – PSI can be set from 1100 – 1500 PSI
All other units – PSI can be set from 1500 – 1800 PSI

After we have addressed the correct PSI setting on the rinse pump with the customer, we get the question on how to adjust that pressure. Every HP rinse pump on a Flexo Wash anilox unit should have a pressure regulator attached to the rinse pump. Now, the styles of these regulators have varied over the years, but the basic operation is the same (although we have seen the odd pump or two where someone had taken the regulator off!).

Solution #1: Turn the Knob on the Regulator Clockwise

To increase the rinse pressure, turn the knob on the regulator clockwise. If you turn that knob and don’t see an increase in the rinse pressure, then there are a few things to check.

First of all, you need to make sure you are getting water to the HP pump. A lot of times, the water inlet solenoid will get stuck closed, even though the coil is energized (but you need to make sure the coil is getting power). If you don’t have any water running to the pump, you won’t get any pressure and can damage the pump and or the motor.

Secondly, there should be a cap on the end of the pressure regulator handle. Once again, the type of regulator may vary on your unit, particularly if it is older than 2006 or if someone has replaced the original regulator with one not from Flexo Wash. Remove that cap and you will see a jamb nut and Allen screw. While the HP pump is running, you can back that jamb nut off (counter clockwise) and then turn the Allen screw clockwise. This should increase the pressure readout on the HP gauge. Tighten the jamb nut back down and now the regulator is set at that particular PSI. You will not be able to increase the pressure past that set point but you will be able to back the pressure off by turning the handle counter clockwise.

Solution #2: Look at the HP Interior Hose

If that trick doesn’t work for you, then you need to take a look at the interior HP hose. If there is a hole in that hose, no matter the size, you will not see an increase in pressure by adjusting the handle on the pressure regulator. Typically, a small hole will show a pressure reading of 500-800 PSI and you won’t get that needle to move on the gauge, no matter how much you crank that regulator clockwise. If you have a large hole, you may get a pressure reading of zero, even though the pump and motor are running. If there is a hole in that hose, then the hose will need to be replaced.

Solution #3: Check the Condition of the HP Rinse Nozzles

Another item to check is the condition of the HP rinse nozzles. If the orifice in those nozzles has opened up over time, then you will not get the correct pressure on the gauge. This is due to the lack of resistance that the HP rinse nozzle is providing. The horizontal slot in the HP rinse nozzle is roughly 3mm long x 1mm wide. If the opening in your nozzle is larger than that, they should be replaced. If the nozzle is partially plugged with debris, then they need to be cleaned out.

Solution #4: Regulator Needs to Be Replaced

If all of the above checks out and you still can’t get that regulator to increase pressure, then the regulator is probably bad and needs to be replaced. Give us a call at the shop and we can walk you through these checks to find out what the problem is and get you back to the correct rinse pressure.

Give us a call at the shop and we can help you troubleshoot the problem.


As always, if you need immediate assistance, call us at Toll Free: 888-493-5396 | F: 888-543-5396

Flexo Wash US

2010 Plantside Drive
Louisville, KY 40299