Your High Pressure Homogenizer Won’t Build Pressure. Here’s what to check.

High pressure homogenizers, or more succinctly, homogenizers are the work horses of many high purity and industrial processing applications, handling products that range from milk to ketchup to flavorings and even grease and glue. So when you fire up your homogenizer after a long weekend and you can’t build pressure, you’re in a bit of a jam. But now is not the time to panic- run through the following check list and you’ll be back up and running in no time.

APV Gaulin High Pressure Homogenizer

Watch & Listen to the Machine Run First

Before you tear the machine apart, turn it on and listen to it run. There are two places we need to evaluate- the pump end and the valve end. At the end of the day, high pressure homogenizers are pretty simple machines- a high pressure pump and a valve. The “watch and listen” technique will help us evaluate the pump end of the machine.

First things first, let’s make sure flush fluid is flowing into the plunger well. This may seem simple, but we’ve seen machines that have gone so long between packing changes that product actually builds up and blocks flush flow to the plungers. This can be a dead give away that the pump end of the machine isn’t functioning right.

Next, verify product is entering the machine at a sufficient feed pressure and make sure it’s leaving the machine at an expected flow rate.

Finally, let’s try to build some pressure and listen to the machine. If you hear loud banging, there’s a good chance you’re cavitating, which can affect homogenization pressure stability. Conversely, if you don’t hear anything, if the machine is running almost too smooth and you can’t hear the suction valves “clicking” back and forth, that could be a sign that the suction or discharge side of the pump is “plugged” up. Yes, we want to hear a rhythmic clicking on a high pressure homogenizer.

If the machine sounds good, but you’re suddenly unable to build pressure on both the first AND second stage of a two stage machine, it’s likely an issue on the pump side of the machine. So what do you do? Proceed to the next section of our check list.

Remove Protective Covers & Check Belts & Hydraulic System

The next thing will want to do is remove the protective covers on the machine, specifically the side panels that give us access to the drive belts and hydraulic pump (for hydraulically actuated machines). Machine belts should turn relatively easy and not be too tight. If they are, that’s a good sign that product has made it past the packings and begun accumulating in the block. We recently saw a machine that ran an adhesive product that literally glued the plungers into the cylinders.

On hydraulic machines, we’ll want to inspect the hydraulic system. Verify that the hydraulic pump is running, able to build pressure (usually there’s a switch to confirm this) and has a sufficient amount of hydraulic fluid in the system. If the hydraulic powerpack is found to be the issue, resolve it and you should be good to go.

If the hydraulics seem fine, please proceed the check on our list.

Remove Front and Discharge Covers, Inspect Packings & Valves

Next, we’ll want to take a closer look at pump side of the machine. If the balls on the suction side aren’t able to adequately seat, we’ll see slip in the machine and won’t be able to build pressure on the homogenizer valves.

To check this, first, remove the front covers on the suction side of the pump. Next, remove front throat bushings, springs, balls, valve guides, packing, packing adjusting ring, and plungers. Inspect each part. Remember, the packing adjusting ring should have about a 0.030” clearance on the plunger. If the adjusting ring is fused to the plunger, that’s a good sign you have a problem. If a spring is broken or your were cavitating your machine and broke a ball or damaged a valve seat, we’ve also found the culprit.

If everything on the suction side looks good, let’s move on to the discharge side of the pump and take a look at the valves below the top covers. Same routine here- remove the covers and inspect the valves. Are the springs intact? If there any products or solids lodged in the valve? Do the valves or seats appear to be worn? Any of these issues will make it difficult for your machine to build pressure.

After inspection, if everything on the suction and discharge side looks good, replace the packings and rest assured it likely isn’t the pump side of your machine. It’s now time to take a look at the homogenizing valve components.

Inspect First and Second Stage Homogenizing Valve Components

If what we’re observing is only reduced pressure capability or decreased performance on just one stage (vs. no pressure on either stage) or a lack of pressure stability, that should give us a clue that our problem is with one of our homogenizing valves. To check the homgonezing valves, start by removing the discharge connection of the machine and pulling the second stage homogenizing valve. Inspect the valve seat and top part and look for the familiar wear patterns depicted in the machine manual. Remember, the homogenizer valve is made up of the valve seat and what is called the valve “top part” in the manual. Both feature pressure lapped faces and any wear can great impact the machine.

If wear is found, replace the necessary components, reassemble the valve and repeat on the first stage homogenizing valve.


At the end of the day, a Gaulin high pressure homogenizer is a relatively simple machine- it’s a high pressure plunger pump with a valve. If you follow the steps above and follow good preventative maintenance practices on your machine, you’ll be back up and running, building pressure in no time.

And if these steps don’t work for you and you continue to have issues with a machine, contact a Triplex Sales Engineer today. We have factory trained repair technicians ready to visit your site and evaluate your machine today!

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