scottyreef Posted March 9, 2009 Share Posted March 9, 2009 I have had some inquiries on what are Peristaltic pumps are and how they work so here is a quick write up ( with aide from Cole-Palmer website) Each pump system is divided into three parts: pump head, drive, and tubing. The pump head consists of the rotor and housing; the drive creates the force needed to move the rotor; and the tubing acts as the pump chamber. These three parts pump fluid by following these steps: The tubing is placed into the tubing bed—between the rotor and housing—where it is occluded (squeezed). The rollers on the rotor move across the tubing, pushing the fluid. The tubing behind the rollers recovers its shape, creates a vacuum, and draws fluid in behind it. A "pillow" of fluid is formed between the rollers ( with two roller application a vaccuum is created but and a check valve is needed so no possible back siphon can occur). This is specific to the ID of the tubing and the geometry of the rotor. Flow rate is determined by multiplying speed by the size of the pillow. This pillow stays fairly constant except with very viscous fluids. the tubing is the pump chamber. The elasticity of the tubing provides suction lift; its strength provides pressure handling ability; its flexiblity determines pumping life; its bore determines the flow rate, and its wall thickness determines pumping efficiency. As i stated before if you use a two roller type pump (like the one below) you need to use a one-way check valve (always on the suction side) ensures positive progress of the fluid through the dosing line while eliminating back-siphoning Tubing life is inversely proportional to pump speed. Minimum speed gives maximum life. You should always size your pump to the largest tubing size to the slowest RPM Increasing Tubing Life A tubing failure is defined as one of two conditions. 1. The tubing wears out and breaks. It generally splits along the longitudinal axis where the largest amount of stress is being placed on the tubing (see diagram). A piece of tubing has a finite # of times it can be compressed before breaking. This is a function of the tubing material and the wall thickness to inside diameter (I.D.) ratio. 2. A loss of 50% of flow rate The tubing fatigues or loses its ability to snap back to its original shape when it is released from the rollers. The flow rate decreases significantly because the vacuum created behind the roller as the tubing regains its shape decreases with fatigue. Therefore the fluid will not be pulled through the pump head as quickly. Figure A shows a cross sectional area of tubing. Figure B shows the same piece of tubing compressed by the rollers in the pump head and Figure C shows the fatigued tubing. Like #1 above, this is also a function of tubing material and wall thickness to I.D. ratio. Keeping these points in mind, here are some ways to increase the life of your tubing: 1. Slow down the drive speed This decreases the frequency that the tubing is being compressed. To maintain the same flow rate, use a larger tubing size. 2. Choose a thick-walled tubing This will increase the number of compressions required to wear the tubing out, and it will increase its memory capacity. e.g. size 25 and size 15 tubing both have the same I.D. and provide the same flow rate, but size 15 has a thicker wall and will last longer. 3. Select the longest life tubing formulation that is compatible with your fluid Norprene® and Pharmed® have the longest lifetimes, C-flex® and silicone have the next longest lifetime, Tygon® formulations have shorter life, and Viton® is generally the shortest lived (less than 250 hours at 100 rpm). 4. Reduce system pressure Tubing lifetime decreases significantly at higher pressures, especially tubing formulations such as C-flex and silicone which have low pressure ratings. 5. Reduce the occlusion This decreases the stress applied to the tubing every time it is compressed. 6. Avoid sharp tubing bends, especially near the pump head. Run the tubing straight out of the pump head for at least 6-8". This will keep the tubing centered over the rollers. 7. Develop a preventative maintenance program Move the piece of tubing that is over the rollers 6-8" after a set number of hours before it reaches its failure point. Later I make a photo blog on how to set up a Dosing system Scott Link to comment
elite401 Posted March 9, 2009 Share Posted March 9, 2009 Very interesting, thanks for the info. Any word on the group buy? I'm dying to get some peristaltic pumps to keep my dosing more accurate and automated and I don't want to pay $85 a piece. Once again, I'm down for 2-3 pumps if you get that group buy going. Link to comment
scottyreef Posted March 9, 2009 Author Share Posted March 9, 2009 I called Apllitek three times on friday the balls in his court. He told me last time that to get a order going all the pump have to be a standard set-up to cut down on manufacturer time. I think that 3 rpm with 3mm tubing that clears .65ml/min with norprene tubing. i really want to get his going for you guys tl;dr j/k. good info. hahaha Yeah me either i just cut and paste a lot Link to comment
scottyreef Posted March 9, 2009 Author Share Posted March 9, 2009 Here is a actual size tubing reference Link to comment
scottyreef Posted March 10, 2009 Author Share Posted March 10, 2009 I had a question today about Santoprene tubing. Santoprene is a genral term for a Thermoplastic elastomers (TPE) which is a mix of polymers (usually a plastic and a rubber) I am not a big fan of it. Santoprene is a cheap thermoplastic that in my experince is prone to splitting. I comes on many commercial dosing pumps (aquamedic,ReefDoser and cheaper dosing pumps) Santoprene tubing was developed for sale to peristalic degergent dosing companies that make automatic dishwashers and large scale laundry companies. if you pump does have Santoprene tubing its no big deal you just have to watch it. I would highly reccomend Norprene/Pharmed and if you can find it Marprene ( it is the best out there one tube lasts over 5 years with proper cleaning) Link to comment
SmittyCoco Posted March 10, 2009 Share Posted March 10, 2009 Still intrested in the group buy as well. keep us updated ! Link to comment
scottyreef Posted March 10, 2009 Author Share Posted March 10, 2009 I'm still on it. i called them today and he said he could do it but i am wori=king with him on the price still because i didnt factor shipping in from china ( i know but i just found this is the exact same pump as drews doser form bulkreefsupply) Speaking of bulkreefsupply i came across that they are getting rid of 150 peristalic pump (not drews doser) they have 3 types 1.2ml/min, 20ml/min and 30 mil/min for $50 each if you get one of these guys make sure you put a check valve on the suction side of the pump http://cgi.ebay.com/Bare-Bones-Peristaltic...1742.m153.l1262 Link to comment
scottyreef Posted May 13, 2009 Author Share Posted May 13, 2009 I am working on a photo blog of my new dosing pump system. to all of those who wanted to get a cheap dosing pump i am really sorry the supplier that i talked to told me one thing ubut he didnt come through. I woudn't mind talking to bulkreefsupply to set up a group buy of there drews doser if anyone would be interested. my current dosing syetem is Calcium Dosing Masterflex® L/S® fixed-speed drive, 1 rpm http://www.masterflex.com/catalog/product_...asp?sku=0754001 Masterflex® L/S® Quick Load® pump head http://www.masterflex.com/catalog/product_...2124&pfx=HV Cole-Parmer 6404-15 High-Performance Precision Norprene Tubing Size 15 http://www.masterflex.com/catalog/product_...0415&pfx=HV Output= 1.7ml/min @ 1rpm Alkalinity Dosing Masterflex® L/S® fixed-speed drive, 1 rpm http://www.masterflex.com/catalog/product_...asp?sku=0754001 Masterflex® L/S® Quick Load® pump head http://www.masterflex.com/catalog/product_...2124&pfx=HV Cole-Parmer High-Performance Precision Norprene Tubing Size 15 http://www.masterflex.com/catalog/product_...0415&pfx=HV Output= 1.7ml/min @ 1rpm Magnesium Dosing Masterflex® L/S® fixed-speed drive, 2 rpm http://www.masterflex.com/catalog/product_...4002&pfx=HV Masterflex® Standard pump head for L/S® 16 tubing, PC housing/CRS rotor. http://www.masterflex.com/catalog/product_...1620&pfx=HV Precision Standard-Performance PharMed ® Tubing L/S® Tubing Size 16 http://www.masterflex.com/catalog/product_...8516&pfx=HV Output= .8ml/min X 2 rpm = 1.6ml/min I still have to set the times up Link to comment
Waterproof Posted May 18, 2009 Share Posted May 18, 2009 Am I misreading these prices? For the combined drive and head, you spend over $350 each, w/o tubing? Link to comment
scottyreef Posted May 18, 2009 Author Share Posted May 18, 2009 I didnt spend that much I got everything but the tubing in a whole sale lot for pharmacuatical company that was closing but that would be the price if i bought it off the self though. i spent about $70 each with heads if i remember correctly Link to comment
Waterproof Posted May 18, 2009 Share Posted May 18, 2009 I didnt spend that much I got everything but the tubing in a whole sale lot for pharmacuatical company that was closing but that would be the price if i bought it off the self though. i spent about $70 each with heads if i remember correctly That's quite a deal! Good job! Link to comment
scottyreef Posted June 16, 2009 Author Share Posted June 16, 2009 if anyone looking to get some peristalic pump tubing i am currently getting read to sell a whole bunch so to any who would like some post in this thread with sizes and lengths I want to know what sizes are needed for other dosing pumps out there Link to comment
kennl Posted June 17, 2009 Share Posted June 17, 2009 Hey Scotty, I'd be in for a group buy of those drew's dosers from bulkreefsupply. It appears on the site that they are out of stock currently, but I send Andrew an e-mail over there to find out when they would be back in, and some pricing as well as quantity minimums. Hopefully will hear back soon and Ill post on this thread. Best, Kenn Link to comment
Recommended Posts
Archived
This topic is now archived and is closed to further replies.