Replacing the water lines in a 16-050 heat exchanger

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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 cooling fan problem

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16-025 and 16-050 radiator cooling fan

16-025 and 16-050 radiator cooling fan












The heat exchanger cooling fan used on the Physical electronics 16-025 and 16-050 heat exchangers which are used to cool the x-ray sources on an XPS system can run slowly as the fan motor ages once the bearing lubricant begins to dry up. The result of a slow fan is that the anode will run warmer than normal and possibly melt.  At a minimum reduced cooling will shorten the anode lifetime.  The 16-020 heat exchanger has a fan that is attached to the pump motor, so it will not have this problem unless the pump motor fails.

The symptom for a slow heat exchanger fan is that with the source at full power after 20 minutes of operation the water lines to the x-ray source will be very warm or even hot  rather than slightly warm.

To test the fan you can feel how much air is coming out the back side of the radiator when the 16-025 or 16-050 heat exchanger is on.  The radiator will slow down the airflow, but it should still be a reasonable amount of air that escapes out the back side of the radiator.  If the fan looks like it is spinning slowly and there is minimal airflow then the fan should be replaced.

If you want to test the actual RPMs of the fan you can use a non-contact laser tachometer (available for as little as $15.00).  Or you can use an audio method as shown in this video on YouTube that uses Audacity:

The fan motor should spin at 1650 RPMs.

If you determine that the fan should be replaced (or if you want to as a preventive measure if your heat exchanger is 20 years old), here is the model number information –

Manufacturer – Orion

Fan, AC, 230V, 254 X 89mm, Round, 547CFM, 35W, 55dBA, 1650RPM

Manufacturer part number: OA254AP-22-1TB

Allied Stock # 70103674

It is held in place with some radiator mounting rods that are available at most auto parts stores.  Look for Hayden Nylon mounting rods with vibration pads.

Nylon mounting rods

Nylon mounting rods














In addition to the cooling fan, if the pressure indicator on your 16-050 heat exchanger bounces during operation you should consider replacing the water pump as well.  RBD Instruments provides the water pumps.   The 16-020 and most 16-025 heat exchangers do not have a pressure gauge.

And of course, make sure that the radiator is free from dust as being covered with dust will also reduce the cooling efficiency of the 16-020, 16-025 or 16-050 heat exchangers.   Refer to the RBD TechSpot post Heat Exchanger Preventive Maintenance for more information on dust and the radiator.

Heat exchanger preventive maintenance will prolong the anode lifetime on your 10-610 mono chromator anode and prevent a costly and time consuming anode meltdown.

Kratos Monochromator adjustment

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This Kratos monochromator adjustment procedure is used on the Kratos Axis, 165, Ultra and Nova monochromators.

Steps involved in optimizing the performance of the Al Monochromatic x-ray source:

First, load a sample bar containing a grid alongside a clean Ag foil sample at the same height.

  1. Using the Mg source image the grid to locate the height of the auto stage that gives the best focus. Move across to the Ag foil sample.
  2. Using the Mg anode find the BE position of the Ag 3d 5/2 peak. This method requires that the calibration of the energy scale of the instrument is correct.
  3. Using the BE position obtained with the Mg dual anode switch to the mono source and begin tuning the source position in conjunction with the crystal settings as detailed below.
  4. The image below shows the mono crystal adjustment mechanism. First undo the locking screw. (Rather than just loosening the locking screw, it sometimes helps to use the locking screw as a counter drive against the micrometers to enable a finer adjustment on the crystal mechanism). Micrometer A tilts the crystal left and right moving the mono spot in the x-axis on the auto stage. This can be carefully adjusted to optimize the count rate on its own (no interaction with other parameters). Similarly, there is a tilt adjustment on the mono source that changes the source to crystal distance that can be adjusted for maximum count rate at this point.
  5. The micrometer on top of the mechanism (marked “Do not adjust” in the image) changes the distance between the crystal and the sample. (After initial factory set up …i.e. for normal maintenance procedures…anode changes etc… this will not need re-tuning).
  6. Micrometer B tilts the crystal to move the mono spot along the y-axis of the auto stage (towards and away from the dual anode source). This micrometer always needs to be adjusted in conjunction with the linear movement of the mono x-ray source itself. When the mono source position is changed it moves the refracted beam on the sample so the tilt adjustment is required to move the mono spot back to the analysis position to maximize the count rate.
  7. The linear drive on the mono source itself should be adjusted in small increments. At each new position micrometer B is used to move the beam spot back to the analysis position (by maximizing the count rate). The best method is to tilt the crystal carefully through the maximum once or twice and make a note of the best count rate obtained.

Next, move the mono source a short distance (this will decrease the count rate). Now repeat the adjustment on Micrometer B to bring the count rate to a new maximum. If the new maximum is higher than the previous one continue the process moving the source in the same direction until the new maximum is lower than the previous one. Then move the source back to the previous setting and re-optimize.

If at the start of the procedure the second maximum is lower than the first, reverse the direction of movement of the mono source and continue the process in that direction to find the best “maximum” count rate.

Once the set up is close to optimum performance more improvement can sometimes be obtained by setting up the tuning using the 110um selected area instead of large area “hybrid” mode. (Starting with the 110um aperture is sometimes difficult due to the lower counting rates).

The locking screw should finally be re-tightened in conjunction with small final adjustments of the micrometers to maintain the maximum count rate. The locking screw may push the crystal position slightly as it is tightened.


Installing parts using Au seals.

When installing using Au wire seals it is essential to locate the seal in the correct position. The seal should be resting snugly on the shoulder formed above the main flange.





This way when the 2 surfaces come together the Au wire is ‘boxed” in and compressed.




If the Au seal is stretched or is not a tight fit on the shoulder and therefore “hangs” over the edge of the shoulder above the flange it will be pinched as the flanges are pulled together and NO SEAL CAN BE ACHIEVED NO MATTER HOW MUCH YOU TIGHTEN THE BOLTS!

Since the seal cannot be seen after mating up the flanges the only indication of whether the Au seal is in place is the gap between the 2 flanges when they are pushed together. There should only be a very small gap between the flanges <~1mm. If the gap is larger it means the Au seal is pinched.





Water Box Maintenance


With 15kV applied at the anode the water lines act as a conductive path to ground. The first point of contact to ground is at the outlet pipe from the solenoid valve (above the valve in the water box. (The water tube goes from there to the supply pipe on the anode). The other point is where the return line from the anode attaches to the flow switch (below the flow switch)






These are the most like places for corrosion due to the voltage difference. Check and clean out or replace these fittings to bring up the flow rate.

Also remember to check the in-line filter. If there is a drop in pressure across the filter as indicated by the pressure gauges, the filter may need to be replaced.