Troubleshooting a Plate Heat Exchanger

Posted by Morgan Byres on

You don't have to be an experienced mechanic to troubleshoot your plate heat exchanger (PHE). Are you having issues? PHE’s are quite durable (however, dropping them is not recommended) but can face performance issues on occasion. The three main issues that occur with PHEs are: leaking within the unit, leaking outside the unit, and pressure drop. These issues are usually easy to diagnose and fix!

Leaking outside of the unit

Liquid leaking out of the unit is usually a result of damage to the gaskets or it may be the result of an error in the assembly of the unit. Start by checking if the distance between the front plate and the pressure plate has changed (commonly known as “Measure A”). You should have been given this measure when the unit was sent to you. If this measure is larger than normal, the unit needs to be tightened, make sure to tighten all of the bolts equally (you don’t want a lopsided unit). If this measure is correct or the unit keeps leaking after it is fixed, mark which plates are leaking, then disassemble the heat exchanger and inspect the plates. The marked plates should be regasketted. Instructions on how to regasket can be found in our Heat Exchanger manual (located on the manuals page on our website).

(Quick Tip:  Papers can be easy to lose, so we decided to be neighbourly and punch the A measure directly onto the front of the PHE and we put it in the drawings we sent with it. )

Leaking within the unit (liquids mixing)

If the liquids inside the unit begin to mix, it is because the plates are leaking within the unit. This is most likely a result of a perforated plate (actually, that is almost definitely the cause). To figure this out you’ll need to run a test (don’t worry you don’t need to be a rocket scientist). The general idea is to fill the unit with water, but only pressurize one side. If the other half of the unit begins to overflow then it is clearly being sabotaged by a perforated plate. To begin, apply constant water pressure (NEVER use compressed air with your PHE) to one side of the unit, then fill the other side of the unit with water, but do not continue pressure on this side. Open the connections on the side filled with water, if a plate is perforated the pressurized side will leak into the side full with water, causing it to overflow and allowing water to spew from the connections (be prepared with a squeegee or mop on hand). If it’s a two section heat exchanger, each section must be tested separately. If a plate is perforated, disassemble the unit and inspect the plates with crevice detection liquids. If you are curious about how to disassemble your unit, feel free to check out our heat exchanger manual, located on the manuals page of our website.

Performance of the PHE with regard to heat transfer and/or pressure drop is abnormal

Is your PHE just not working as well as it used to? We would love to sell you a new unit, but it would be easier for you to test for a couple common causes of low flow or performance. Poor performance is the most common issue with heat exchangers; there are several main causes: an error in the platage, too little water flow, an accumulation of debris within the unit, or the hook up is just plain wrong.

Checking the platage: If the plates are assembled in the wrong fashion, it can create a deadzone, causing the unit to bypass a portion of the plates. Review the plates and ensure they are assembled in the lovely honeycomb pattern shown below. It can be hard to notice the change in the pattern right away, so look very carefully for any backwards plates. Conformity is important when it comes to PHE plates. If a plate is out of place, you need to you fix it. To do this you must open the heat exchanger (disassembly and reassembly instructions are in our PHE manual) and flip the plate that is backwards. Once your plates are all aligned and pretty again, close it and test the pressure again.

Too much debris: If there is a buildup of debris in the unit, it will negatively affect performance. Run a standard CIP cycle to clear out any excess debris, if the debris does not clear, manual cleaning may be necessary. Manual cleaning is fairly straightforward, but once again I will redirect you to our comprehensive heat exchanger manual on the manuals page of our website.

Insufficient water flow: It isn’t necessarily your poor little heat exchangers fault. If the water flowing to the unit has insufficient flow, it will cause the heat exchanger to lose productivity. Check the pressure and flow rate of the water and ensure that it meets the designated threshold.

Hook up is wrong: If the setup is wrong, the unit will function at an extremely low efficiency. Review the operating and setup instructions (we know we sent you some) to ensure that it is being used correctly. Remember counter current flow is required.

A couple things to keep in mind

Plate heat exchangers are notoriously difficult to put together if you do not know the configuration of your plates. Please DO NOT take your plates out without numbering them first.  It is very easy to mix up the direction of a plate (ruining the pretty honeycomb pattern) which will bypass a section of the plates. Also, the pesky centre plates (which allow for multiple passes) need to be where we put them, so ALWAYS number your plates - and keep track of their orientation - when removing them.

In conclusion

If after trying all of these tests your PHE is still not working, please give us a call and we will do our very best to get your system back on track!  Whatever the cause, we have solutions and are always happy to help.

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