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.
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).
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.