Introduction
The use of peristaltic pumps in tablet coating applications is well established. Peristaltic pumps:
- offer very good flow rate stability
- have exceptional flow rate range and control
- have full self priming capability
- handle viscous and abrasive products with ease
- have the most hygienic design of any pump type
- are the easiest to clean of any pump type
They also offer a multi-channel flow from a common drive, providing an individual pumped feed for larger coaters using several spray guns.
Silicone and STA-PURE tubing have been standardised for most common aqueous coating formulations. However, there has not been a suitable tube for pumping coatings which are methylene chloride based. This has now changed with the introduction of a CHEM-SURE tube developed by W L Gore & Associates, working in association with Watson-Marlow Bredel.
Features and benefits
CHEM-SURE is a composite of PTFE and a high grade fluoroelastomer, which offers a unique combination of features:
- Excellent chemical resistance, approaching that of pure PTFE
- Excellent pumping life
- USP VI approval
- CE and US food grade approval
- Very low extractables
- Excellent flow rate stability
Excellent chemical resistance
The tube offers excellent resistance to a wide range of chemicals including acids, bases, organic solvents, esters and ketones. In laboratory tests, samples immersed in a wide range of chemicals exhibited negligible reaction. The test chemicals included - among others - methylene chloride, toluene, acetone, 36% HCl and 70% HNO3.
Excellent pumping life
In both laboratory tests and in production environments, CHEM-SURE has lasted at least 50 times longer than other fluoroelastomer or viton equivalent tubes. Pumping methylene chloride under transfer conditions (i.e. zero pressure and suction), the tube life was in excess of 1,300 hours at 200rpm.
USP VI approval, CE and US food grade approval
CHEM-SURE is unique in offering both excellent chemical resistance and medical and food approvals. No other peristaltic pump tube offers this combination of features
Copies of test certificates are available on request.
Very low extractables
In comparative tests, CHEM-SURE had the lowest level of extractables by a significant margin. The results are summarised in the table below:
| Ethyl acetate | Methylene chloride |
CHEM-SURE | 0.013% | 0.005% |
Conventional fluoroelastomer tubing (viton or viton equivalent) | 1.73% | 0.026% |
Thermoplastic elastomer | 134.4% | 39.8% |
(All samples were sonicated in solvent at 25 deg c for a period of 2 hours. Residue was corrected for solvent blank)
As can be seen, the level of extractables for CHEM-SURE is lower than 20% than that of a viton equivalent. Viewed in conjunction with the medical and food grade approvals, CHEM-SURE is clearly the best for pumping methylene chloride and methylene chloride based products. Other tube materials could result in coatings contaminated by the tube material.
Excellent flow rate stability
CHEM-SURE gives excellent flow rate stability. This increases the interval between calibration runs and reduces the amount of operator intervention required.
The tube also exhibits excellent stability across a wide range of ambient and product temperatures.
Availability
CHEM-SURE is available in a range of sizes to suit Watson-Marlow pumpheads. These are summarised in the table on the following page.
For further details on the tube, or to request a sample for trial, please contact your local representative or the Technical Support Office at:
Watson-Marlow Bredel,
Falmouth,
Cornwall
TR11 4RU
England
(Tel) +44 1326 370370
(Fax) +44 1326 370360
International Contacts
Fluoroelastomer/PTFE tube range
Tube bore
| Tube wall | Product code | Suitable pumpheads |
mm | mm | | |
| | Plain tubing | |
1.6 | 1.6 | 965.0016.016 | 313, 314,
501RL
501RLG
501RLC
501RLCG |
3.2 | 1.6 | 965.0032.016 |
4.8 | 1.6 | 965.0048.016 |
6.4 | 1.6 | 965.0064.016 |
8.0 | 1.6 | 965.0080.016 |
1.6 | 2.4 | 965.0016.024 | 313D2, 324D2
501RL2
501RL2G
501RL2C
501RL2CG |
3.2 | 2.4 | 965.0032.024 |
4.8 | 2.4 | 965.0048.024 |
6.4 | 2.4 | 965.0064.024 |
8.0 | 2.4 | 965.0080.024 |
6.4 | 3.2 | 965.0064.032 | 620R |
9.6 | 3.2 | 965.0096.032 |
12.7 | 3.2 | 965.0127.032 |
15.9 | 3.2 | 965.0159.032 |
| | 620 elements | |
12.0 | 4.0 | 12 x 4.0 | 620RE
620RE4 |
17.0 | 4.0 | 17 x 4.0 |
| | Double 'Y' elements | |
1.6 | 2.4 | 965.E016.K24 | 505L
505LG |
3.2 | 2.4 | 965.E032.K24 |
4.8 | 2.4 | 965.E048.K24 |
6.4 | 2.4 | 965.E064.K24 |
8.0 | 2.4 | 965.E080.K24 |
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