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Abstract:

An alternative to the previous Honlite 1000mL/min peristaltic pump was required: our department cannot buy from Aliexpress or Alibaba, and Honlite only sells their pumps on those sites. Luckily, I found a 24DC, 2200mL/min pump for $99 on Amazon! Let's discuss why this is a big deal and how it will work.

Discussion:

Peristaltic pumps generally come in two categories: cheap with a low flow rate, and extremely expensive with a high flowrate. Perform a simple google search for "high flow rate peristaltic pump", and you'll quickly realize why the first design tried to get away with two $12 pumps in parallel. On top of this, high flow rate pumps often require greater supply voltages or even an AC current not compatible with the current electronics. 

The 2200 mL/min pump, despite its 24VDC rating, has a very affordable price for the specs. The 2200 mL/min is over 4 times the minimum requirement of 530 mL/min, based on the EPA's recommended line velocity of 60cm/s or greater (source) and our chosen tube ID of 0.17'' or 4.3mm. The manufacturer, in an answer to a customer's question, said the user should expect their pump's flow rate to increase linearly with supplied voltage. Based on this, we could expect the pump to provide a flow rate of roughly 1100 mL/min when powered from our system (12VDC). 

Other Considerations:

The new pump comes with barbed fittings on either end of its soft tubing that are too large for the teflon tubing ID of 0.17''. Barbed x Compression fittings are an awkward, hard to find (possibly non-existent) kind of fitting so instead a Barbed x Barbed reducing fitting should be purchased. US Plastic doesn't stock anything close to what we need, but two of these 3/16'' x 3/8'' stainless steel fitting from KegWorks should do the trick since 3/16 is 0.1875.