FAQ : Laboratory Peristaltic Pumps

How do I choose between a peristaltic and a syringe pump?

Assuming both pumps work at the flow rates you require, the factors that favor a peristaltic pump are: (1) the ability to pump continuously from a reservoir and (2) typically lower cost per channel. The factors that favor a syringe pump are: (1) higher accuracy (about 1% for a syringe vs. 5% for a peristaltic) and (2) very smooth flow.

How do I choose between your model P720 and model P820 pumps?

Since the pump heads on our P720 and P820 pumps are identical, the choice comes down to convenience of controls and cost per channel. Most people choose the P820S pump with an P820C controller when they are running multiple experiments at once since the controls are centralized and the cost/channel is lower. Use the P720 pump when you need a stand-alone device with the safety of a battery backup.

How do I choose the right tube set?

Choose the tube size to match your required flow rates, choose the tube material based on the types of solutions your will be pumping, and choose the connectors that will match the rest of your system. Refer to our Tube Set Selector Chart for details on P720 and P820 tube sets.

What are the absolute minimum and maximum flow rates of your peristaltic pumps?

The absolute maximum flow rate of our P720 and P820 pumps is 3 ml per minute (180 ml per hour) using the largest tube set. The minimum flow rate is 0.2 ml per hour with our standard set up, though we can go lower with gear ratio changes. Our P625 series of peristaltic pumps for OEM applications can deliver up to 22 ml/min, down to less than one microliter per minute. One you have chosen a particular tube size and, in the case of the P625 pumps, the pump motor's gear ratio, you can control the flow rate within a 1:20 range with the dials on the pump or the external speed control signal.

How can I minimize pulsations?

We have contoured our pump head so that the roller disengages the tube as gently as possible, but a slight pulsation will still occur when the roller moves off the tube and the tube expands. These pulsations are of no consequence to most applications, but if they are causing problems in your system, try to better match the inlet and outlet pressure by raising or lowering the source reservoir. A slightly higher inlet pressure can frequently cancel the pull back effect.

Do I need to recalibrate the pump when I change the tube set?

Our standard tubes sets typically match within ±10%, so if you need accuracy higher than this you should recalibrate. We can provide matched tube sets to customers that order large quantities of the same type. Call for details.

Can I use regular 9 volt batteries in your P720 pumps?

Yes. Regular alkaline batteries will run the pump continuously for about 18 hours; rechargeable NiCads will run for about 2.5 hours. We suggest lithium batteries because they will run for about 30 hours and have unlimited shelf life.

How can I use Instech's pumps to maintain constant fluid levels in perfused tissue chambers? [USER TIP]

Instech can provide you a P720 pump with a deliberately unbalanced dual channel tube set specifically for this application. Use the channel with the higher flow rate to pull off solution and the other channel to infuse. See this application note for more details.