Our research group just bought a SMPSS 3936 NL88-N. We are having some problems because this equipment came without their neutralizer. Does anyone bought this equipment without this accessory? Our sample flow is really low (0.04lpm), we think the problem is that the SMPSS does not has this neutralizer.
Dear Dayana,
before the particles enter into the DMA, it is necessary to charge them to a known charge distribution. The electrostatic classifier Model 3936-TSI typically uses a neutralizer of kr-85 for charging to that charge distribution.
Kind regards,
Mar
Thanks Mar, our problem is that we do not have this neutralizer. We bought it without knowing this. Kind regards.
Now we know that this equipment needs a neutralizer and do not work without it. They sale this equipment without the neutralizer, apparently they sale them separately.
I would suggest to contact the company who sold you the SMPS. A neutralizer is necessary to charge the particles to a known charge distribution. TSI is currently commercializing also non-radioactive neutralizers that might work for your case. I think an addition challenge for you is the sampling flowrate. To control a flowrate of 0.04 lpm is not easy and you need a sheat flow of around 0.4 lpm. The noise is going to be very high in your results. What is your application?
We just bought the X-rays neutralizer, although it not radioactive we are doing all the paper work as it radioactive (Government is considering it radioactive). We are using it for air quality research, excuse me we pretend to use it for air quality. Now we are just waiting.
Dear Dayana, the algorithm that calculates the size distribution based on the number of particles the CPC counts "assumes" that the aerosol is in charge equilibrium (=Boltzmann distribution). This is why the neutralizer is required. If you are measuring ambient (=aged) aerosols, the charge distribution usually is close to Boltzmann distribution.
Without having seen your instrument it is just a best guess, but I assume that you do not have put "a brigde" into the place where the neutralizer usually sits. This would explain why you do not get the correct flow: The aerosol inlet on the classifier front is not connected to the DMA inlet. If you want to start measuring while waiting for the paperwork to get done, you can do the following: On top of the classifier 3080 you find a circular black cap fixed with two screws. This is where the neutralizer will be placed. You can use a 8.62 inch long stanless steel tube, outer/inner diameter should be the same as the tube of the aerosol inlet. Use a little bit of the grease you find in the SMPS accessory. Once you set this tube in place your inlet flowrate should read the same as your CPC flowrate.
I hope this helps. In case you have questions: Send me a message and I will forward you the contact data of our TechSupport.
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