16-050 Heat Exchanger Flow Switch replacement procedure.

The original flow switch for the 16-050 heat exchanger used 220 VAC for the input power.

About 10 years ago that flow switch was discontinued and was replaced with a similar model that used 120 VAC for the input power.  A 220 VAC to 120 VAC step down transformer was also needed.

Very recently, the 120 VAC input power flow switch was discontinued, and it has been replaced by another version that uses 24 VDC as the input power.  To provide 24V DC to the replacement flow switch a small 220VAC to 24 V DC power supply is needed.

This blog post will provide step by step instructions on how to install the new 24V DC flow switch and power supply into a 16-050 heat exchanger.

Step one is to drain the water from the heat exchanger.  The easiest way to do that is to remove the IN and OUT couplers from the X-ray source and then connect those to the IN and OUT lines. Mark the IN and OUT water lines to make sure that you do not get them mixed up.  Hold them over a clean container (such as a plastic waste basket) and then turn on the 32-095 or 32-096 X-ray source control. 

The 16-050 will turn on and water will come out of the source IN line.  After about 9 seconds the 32-095/96 will shut down the 16-050 heat exchanger due to insufficient flow.  Turn the 32-095/96 OFF for a few seconds, then back ON.  Repeat several times (it might take 10 to 15 times) until water stops coming out of the source IN line and the pump starts to make noise.  This will drain most of the water out of the 16-050.  You want to use a clean container for the water so that you can reuse the water.  Or you can replace the water after the flow switch has been replaced with distilled water from a grocery store.  Lab DI water does not always work.

After the water has been drained, turn the 16-050 heat exchanger front panel power switch to OFF.

Next, trace the power cord that is on the back of the 16-050 into the electronics console and unplug the power cord.  Make a note of where that power cord plugs into so that you can plug it into the same receptacle later.

Turn the 16-050 front panel power switch to ON just to make sure that the 16-050 power cord is unplugged.  Verify that the 16-050 motor does not turn on and then turn the 16-050 heat exchanger front panel power switch back to OFF. Do not work on the 16-050 if it is still plugged in!

Remove the top cover on the 16-050.

Remove the small cover that is located just behind the 16-050 power switch.  There are 4 nuts that need to be removed then the cover comes off.

Remove the wires that go to the flow switch.  Those will be TB1 sections 1, 2, 5 and 7.

Remove the old flow switch.  Use your phone to take pictures of where the IN and OUT lines connect on the flow switch.

Install the new flow switch making sure that it is connected EXACTLY the way that the old flow switch was.

Route the new flow switch wires up to where the old flow switch wires were.

The wires need to be connected as follows:

RAVCV04-24 power supply:

Blue to TB1 7

Brown to TB1 5

Red to Flow Switch Brown

Black to Flow Switch White

Flow Switch:

White to RACV04-24 Black (use twist nut)

Brown to RACV04-24 Red (use twist nut)

Red to TB1 2

Black to TB1 1

Green – Not used.

This drawing shows the connections –

Verify that the wires are all tight and then replace the little cover using the 4 nuts.

Reconnect the couplers and water lines to the X-ray source.  Make sure that you have the IN and Out going to the correct ports on the X-ray source.

Pour most of the water back into the reservoir or use 2-3 gallons of distilled water from a grocery store.

Plug the 16-050 power cord back in and then turn on the 16-050 front panel power switch.

Turn on the 32-095/96 and the 16-050 motor should turn on.  It will turn off after 9 seconds.  Turn the 32-095/06 off and then back on to reset the pump.  Do this a few times until the air bubbles work themselves out and the 16-050 pump motor stays on. 

You will need to top off the water reservoir once the water fills up the lines.  Do not overfill!

If the 16-050 will not stay on even when the water is full (close to the upper line on the water level indicator on the back of the 16-050) then the flow switch may need to be adjusted.

The flow switch adjustment potentiometer is on the back of the flow switch under a label. It is a small, slotted screw.

Try turning the flow switch a few turns CW and then turn on the 32-095/96.  If that does not work, try a few turns CCW plus a few more turns.  Once you get it to where the 16-050 pump stays ON then you can slowly turn the potentiometer the opposite direction until the red interlock light on the 32-095/96 turns ON, then adjust the potentiometer 1.5 turns the other direction until the red interlock light just turns off. The idea is that you want to set the potentiometer so that the 16-050 pump is ON when you have water flow, but you want to be somewhat close to the edge so that the 16-050 pump will shut off when the flow drops. 

Typical flow rates are 1.1 GPM for XPS systems with a 10-610 mono-chromator source and up to 1.8 GM for systems that have only a single 04-548 dual anode X-ray source.

The RBD Instruments Part number for the kit that includes the 24V flow switch and the power supply is FLOW-SWITCH-24-Kit.

For more information please contact RBD Instruments here – https://rbdinstruments.com/contact.html

Deionizer flow restrictor

Deionizer flow restrictor for PHI X-ray source heat exchangers

This post is a reprint of a tech tip that we published in our fall 2008 Service Detail newsletter. This exact problem came up recently and so I thought I would resurrect this tech tip for educational purposes. In the recent case we knew that the leakage current was very high and it had been several years since the deionizer cartridge was replaced. Replacing the deionizer cartridge was the logical solution. Replacing the cartridge did solve the problem for a while, but within a very short time the leakage current problem returned. Cleaning out the flow restrictor as described below solved the problem.

If you need replacement water filters or deionizer cartridges for your PHI 16-020 or 16-050 X-ray source heat exchangers that are available at this link – PHI Optics Parts

Deionizer flow restrictor inspection and cleaning procedure:

The 04-500 and 04-548 15kV dual anode x-ray sources are water cooled by a closed loop radiant heat exchanger (model 16-020, 16-050) which includes a built in water filter and deionizer cartridge. Since the anode floats at 15kV, the water must be kept in a constant state of deionization to prevent leakage current. If the leakage current is more than 2 or 3 mA at 15kV of high voltage then the leakage current will start to affect the power regulation on the 32-095 or 32-096 X-ray source control. Normal leakage current (the current that is shown on the HV supply current meter when only the high voltage and no power is applied) should be less than 2mA @ 15kV. Once you get up to 3 to 5mA it is time to replace the water filter and deionizer cartridge.  If the leakage is very high (10mA or more) then it is possible that the heat exchanger flow restrictor is plugged up.

Part of the loop in the cooling flow directs about 10% of the water through the deionizer and filter. There is a flow restrictor just in front of the input to the filter and this flow restrictor can become clogged or corroded over time, resulting in reduced flow to the deionizer cartridge and subsequent increased leakage current.

It is recommended that every time you replace the deionizer cartridge and filter (about once every 3 years is typical) that you inspect the flow restrictor and clean it out if necessary. If it is corroded you may need to drill it out with a tiny drill bit (about .030″).

The pictures below show the location of the flow restrictor and how to remove it for inspection. If it is plugged up then drill it out with a small drill bit and clean it before reinstalling it into the flow restrictor connector

This slideshow requires JavaScript.

Heat exchanger preventive maintenance

The 16-020 and 16-050 heat exchangers that are used with many Physical Electronics X-ray sources require a minimal amount of preventive maintenance to ensure that they provide sufficient cooling power.

Typically, the only maintenance that is performed is that the water filter and deionizer cartridge are replaced when the leakage current starts to creep up above 3-to-5mA. The deionizer cartridge helps to maintain the high resistivity of the distilled water that is circulated out to the x-ray source and back to the water tank via the radiator heat exchanger.

As shown in the pictures at the bottom of this post, one thing that is not obvious but should be checked once a year is the space between the cooling fan (in the 16-020) or fan blade (in the 16-050) and the radiator heat exchanger. Dust can collect on the fins of the heat exchanger radiator, which in turn can significantly reduce the cooling capacity of the heat exchanger.

Heat exchanger radiator cleaning procedure:

  1. Turn off the 32-095, 32-096, or 50-096 X-ray source control. This will ensure that the pump motor or air fan does not turn on.
  2. For the 16-050, trace the power cord back to the system and unplug it.
  3. Take the top cover off and remove the 4 screws that hold the cooling fan to the heat exchanger radiator. Unplug the fan power connector and set the fan aside.
  4. For the 16-020, turn the circuit breaker in the back of the unit to OFF.
  5. Remove the side panel to get better access to the heat exchanger radiator.
  6. Use a soft brush and a vacuum cleaner to remove any built-up dust from the heat exchanger radiator fins. If the fins have been bent from lack of care when removing the filter or deionizer cartridges, straighten the fins out with a small needle-nosed pliers or flat tweezers.
  7. For the 16-050, reinstall the fan. If the fan does not spin freely or makes a grinding noise when operated, it should be replaced as a preventive measure. Here is a link to a replacement fan: http://www.alliedelec.com/search/productdetail.aspx?SKU=70103674

Replacement parts for the heat exchanger (such as the deionizer and filter cartridges, flow switch and pump) are available from RBD Instruments at this link: Heat exchanger deionizer parts


Flow rate adjustment procedure:

If the pump has been replaced it needs to be adjusted to the proper flow rate. For the original Procon pumps you need to remove the acorn nut to get access to the adjustment screw. The new RBD replacement pumps do not have an acorn nut. Turn the screw CW to raise the flow rate and CCW to lower the flow rate.

There are 2 possible flow rates depending on which model of X-ray source(s) you have on your system.

If you have only the standard 04-500 or 04-548 15kV dual anode X-ray source, the flow rate should be set to 1.8 GPM.

If you have just the 10-550/560/610 mono source, the flow rate should be set to .9 GPM.

If you have both the standard 04-500/548 and a 10-550/560/610 mono source then the pressure should be set to .9 GPM.

Note that the flow rate is measured with the source(s) connected. The 16-050 has a built-in flow meter which makes this adjustment easy. In the case of the 16-020 (which does not have a flow meter), you need to either

1. Insert a flow meter in series for this adjustment
2. Simply disconnect the outlet of the last source in the string and drain the water into a clean bucket for 1 minute and then measure the amount of water that you collect. It is important to use a clean bucket so that you can reuse the water.

If you have leakage current problems with your source, we have found that draining all the water out of the heat exchanger and X-ray sources and replacing the water with distilled water from a grocery store will restore the water to the correct resistance. The deionizer cartridge (if it is still in good condition) will then maintain the water quality. To test for leakage current, increase the voltage on the X-ray source high voltage supply to 15kV with no power to the filaments and see what the leakage current is. Typically the leakage current should be less than 2mA if the deionizer is working properly. If the leakage current starts to get up to 3-to-5 mA then it is time to replace the deionizer cartridge. For mono sources it is recommended that the deionizer cartridge be replaced whenever the anode is replaced even if the leakage current is fine.

Keeping the heat exchanger radiator clean will help the X-ray source to run cooler, and that will extend the anode lifetime.

This slideshow requires JavaScript.