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Very recently, the 120 VAC input power flow switch was discontinued, and it has been replaced by another version that uses 24 VDC as the input power.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

Replacing the water lines in a 16-050 heat exchanger

In a previous post we showed you how to remove dust from the radiator in a 16-020 or 16-050 X-ray source heat exchanger

For this post we will replace the flow switch, which is used in a 16-050 heat exchanger, and also replace all of the water lines.  The water lines in this particular heat exchanger have become green with contamination from long term corrosion of the fittings and copper X-ray source anode.

We will  remove the motor and pump as part of the hose replacement procedure  and will also clean and lubricate the pump to motor connection.

This procedure will take about 2 hours.   The replacement hose should be clear reinforced braided tubing that is 5/8” OD and 3/8” ID. This type of hose is available from Home Depot, McMaster-Carr, and Grainger. Measure the length of the existing water lines and then add another 10 feet for the16-050 lines.  You may be able to get by with 50 feet but a100 foot roll at Home Depot is only about $50.00.

You will also need 3 gallons of distilled water from a grocery store

First of all, drain as much water as possible out of the water lines. Here is the best way to do that –

Turn OFF the 16-050 OFF and also unplug the power cord from the back of the system. Remove the top cover on the 16-050 and also remove the electrical cover that is located in front left hand corner of the 16-050.

Locate the Crydom Power On relay under the switch cover.

Double check that the power cord to the 16-050 is unplugged.

Move the black output wire from pin one to pin two. Both black output wires should be on pin two.

move wire from here

move wire from here

move wire to here

move wire to here

Remove the quick disconnects from the X-ray source and plug them into the ends of the IN and OUT water lines that connect to the 16-050.  That way, when you turn on the 16-050 one line will have water coming out and the other one will have air going into it.

Plug the 16-050 power cord back in. Hold the water lines over a water tight pail (a plastic garbage container will work well). When you turn the 16-050 switch  back ON, the water will flow out of the end of the water lines.

Turn the switch breaker OFF when the water stops flowing and is mostly spurting air.

(Note, if you have a 16-020 heat exchanger move the Pump power cord to the HV receptacle and the you can control the pump by turning the circuit breaker ON and OFF)

Unplug the 16-050 power cord.

Remove the side covers on the 16-050.

Remove the DI cartridge and water filter. Note the position of the cartridges so that you can replace them in the same locations later.

Remove the pump from the motor (one screw and a clamp) and set it aside. You do not need to disconnect the wires.

Remove the fan (the outer screws in the square metal fan support).

Next, remove the radiator.

Clean the radiator by flushing it with some Alconox or other detergent followed by a thorough rinse out with warm water.

Clean the cooling fins as needed.

Reinstall the radiator

Replace all the water lines one at a time.  Remove a line by unscrewing the hose clamps and twisting the hose off the connector.  If the connector has barbs on it you will need to cut a slit in the hose with a box cutter or utility knife.  Use the old hose section to measure the length of replacement hose then cut the new hose to the same length. Feel free to make the new hoses slightly shorter or longer if that will make it fit better.

Also, to soften the line and make it easier to slide over a barbed connector, dip the line in Acetone for about 20 seconds.  This works quite well.   You could also heat the line with a heat gun on the low heat setting for a few seconds.

When you get to the flow switch,  unscrew the two front panel screws and pull the flow switch away from the fort panel.  If you are going to replace the flow switch, now is the time.  You may need to pull some blanking plugs off of the old flow switch.  Make sure that you put the new flow switch on exactly  the same way that the old one comes off as that is very important for the water flow direction.  Take a picture with your phone before you remove the lines for reference.   Also note the location of the wires in the terminal strip.

Note that the 220VAC version of the flow switch is no longer made and so in a 16-050 you would also need a 220VAC to 120VAC step down transformer. Contact RBD Instruments if you need a replacement flow switch.

Step down transformer mounted in 16-050

Step down transformer mounted in 16-050

terminal strip

terminal strip

16-050 schematic

16-050 schematic

After all of the water lines have been replaced, remove the quick disconnects from the water lines and plug the water lines together.

Reinstall the DI and water filter cartridges.  You should replace both the De-ionizer and filter cartridges if it has been a while (a few years) since the last time you replaced them.  If you replaced the x-ray anode in a 10-610 mono source as part of this maintenance then the deionizer cartridge MUST be replaced. Contact RBD Instruments if you need a deionizer cartridge or water filter.

Reinstall the motor.

Inspect the water pump and clean and lubricate (with grease) as necessary.   The  motor to pump connection can get a lot of debris and some rust accumulation.

Reattach the pump to the motor.

Put one gallon of fresh distilled water (from a grocery store, not lab DI) into the reservoir.

Plug in the 16-050 power cord.

Turn on the 16-050.

Immediately add another gallon of fresh DI water into the resistor as the water will be filling the lines and cartridges.

Check for leaks and tighten hose clamps as needed.

Add more water as needed until the level is correct on the back of the 16-050.  It will take 3 to 3.5 gallons.  Give it some time for the cartridges to fill up, about 10 to 15 minutes before you do a final top off.

If you have replaced the flow switch you can monitor pins 1 to 5 on the Coolant ON/OFF connector with an ohmmeter. With the 16-050 on and water flowing, adjust the potentiometer on the flow switch until the resistance between pins 1 and 5 drops down to 1 ohm or less.

Reconnect the Coolant ON/OFF cable.

Turn off the power to the 16-050 and unplug the power cord from the back of the system.

Confirm that the power cord is unplugged.

Move the wire on the terminal block form pin two back to pin one.

Replace the electrical cover.

Replace the side covers.

Replace the top cover.

Plug the 16-050 back in and turn on the power switch.

The 16-050 should turn on and off when the 32-095/6 is turned off and on.

Turn off the 32-095/6 and then reconnect the water lines to the X-ray source.

Procedure is complete.

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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.

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