What causes pumps to cavitate? And why is my pump so LOUD?

Have questions? We'd love to chat! Send us a message here: www.vikingpump.com/yt
In this Pump Report, Chad covers the causes and symptoms of positive displacement pump cavitation. To learn more or see other Pump Reports, visit our website at vikingpump.com
#VikingPump #cavitation #pumps
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Hi, I'm Chad Wunderlich with Viking Pump. In a previous video we discussed the priming capability of positive displacement pumps, like this gear pump. This is due, in part, to the pump's ability to develop vacuum...but what happens if that vacuum gets too high? Today we're going to talk about cavitation. You're watching the Pump Report. So what is cavitation and how do we diagnose it? Before we get into all that let's talk about how a pump works. In our priming video, the pump develops a low pressure vacuum at the inlet port allowing atmospheric pressure to push the water into this low pressure zone. You can observe the same phenomenon when drinking liquids with a straw. So what happens if the vacuum dips too low? Take water for example: it's widely accepted that water boils at 100°C or 212°F - but did you know that if the surrounding pressure drops, water can boil at a lower temperature? In fact, in Denver, Colorado water boils at 94°C or just over 200°F. This is due to the lower atmospheric pressure at high altitude. When subjected to high vacuum, like at the inlet port of a pump, water can even boil at room temperature. High vacuum at the pump inlet isn't always the result of suction lift. It can be the result of other factors such as suction line restrictions. Here I have two syringes - simple examples of positive displacement pumps. One has a large inlet port and the other is narrow. On the large inlet pump, even if I pull the plunger back quickly, the pump fills without issue. If I use the small inlet pump and pull the plunger too quickly, you see bubbles forming. This is the water boiling as a result of too much vacuum. The collapse of these bubbles and the subsequent effects are cavitation. Here we see a Viking internal gear pump with a clear head so that we can get a better view of the cavitation inside a pump. As the inlet valve is closed, the vacuum increases causing bubbles to form. As these bubbles are carried to the discharge side, they collapse. It's this collapsing of the bubbles that gives cavitation its most well-known symptom: noise. Even Hollywood knows this one: cavitation equals noise. "Captain, we're cavitating! He can hear us!" And these bubbles are taking up volume that should have been liquid. This means that the capacity drops as well. Loss of capacity is symptom number two of a cavitating pump. And the pressures exerted by these collapsing bubbles can be extremely high. The result of frequent cavitation can lead to pitting of the pump internals. For an internal gear pump, this includes the face of the rotor, roots and flanks of the gear teeth on both the rotor and the idler, and at the discharge side of the head. Localized pitting is symptom number three for a cavitating pump. So in review, the symptoms of cavitation include noise, loss of capacity, and if you take the pump apart you might observe pitting of the internals. So for a pump with those symptoms you'll want to confirm that it's cavitation. And to do so you'll want to install a suction side gauge. A vacuum gauge can either confirm that it's cavitation or be an indication that something else is going on all together. To learn more about pump cavitation, other troubleshooting topics, or just to view other Pump Reports please visit our website at vikingpump.com.

[@gcaj85]

Here because of a system warning in Subnautica.

[@greentripleu5670]

I always love a good pump report!

[@rubenmauricio1237]

Thank you for the video. Where should the vacuum gauge be installed?

[@VikingPumpInc]

Vacuum gauges (or compound gauges if the inlet pressure could be positive at times) should be installed at the pump’s supplied gauge port or at a point in the suction piping as close to the pump as possible. You can see an example of each in this video at 1:42 and 0:28 respectively.
1:42 - czcams.com/video/uPV0F091AHI/video.htmlfeature=shared&t=102
0:28 - czcams.com/video/uPV0F091AHI/video.htmlfeature=shared&t=28
If you've got questions about specific pumps, feel free to reach out to us here! www.vikingpump.com/yt

[@nathaniel9184]

Very good report!

[@Al-ut7fh]

I went on Viking pumps to look up more troubleshooting topics, like the video said, and found nothing.

[@VikingPumpInc]

Here's a playlist on various troubleshooting topics: czcams.com/play/PLEWF2-ex7JzZF-86iyegcSXKH387FpdMF.html
Please let us know if there are any topics you'd like covered!

[@greentripleu5670]

Let’s go!!!!