Directive 94/9/EC, commonly known as the ATEX directive, carries obligations to the person who places equipment on the market, in the EU territory, for use in potentially explosive environments. A number of pumps manufactured by Watson-Marlow Bredel are suitable for use in hazardous environments; ATEX compliant pumps from the 500 series are listed below, in Section 2 "Pump models".
All of Watson-Marlow's ATEX pumps have been rated as Group II, Category 2 equipment. The 501RLA pumps are intended for use in gas based environments only. The pumpheads are sold individually (for use with customer specified ATEX drives) and in defined configurations complete with Watson-Marlow ATEX drives.
2. Pump models
The following 500 series pumps are covered by this manual:
501RLA ATEX Pump-heads |
| 501RLA* | 053.0001.A00 | Twin roller for 1.6mm wall thickness tubing |
| 501RL2A* | 053.0001.A20 | Twin roller for 2.4mm wall thickness tubing |
| 501RLGA* | 053.0011.A0G | Twin roller for 1.6mm wall Sta-Pure tubing |
| 501RL2GA* | 053.0011.A2G | Twin roller for 2.4mm wall Sta-Pure tubing |
| 501RLCA | 053.0002.A00 | Close-coupled for 1.6mm wall tubing |
| 501RL2CA | 053.0002.A20 | Close-coupled for 2.4mm wall tubing |
| 501RLCGA | 053.0022.A0G | Close-coupled for 1.6mm wall Sta-Pure
|
| 501RL2CGA | 053.0022.A2G | Close-coupled for 2.4mm wall Sta-Pure
|
* NB: these pumpheads are compatible with a number of Watson-Marlow cased drives. However, the Watson-Marlow cased drives are not ATEX compliant and must not be used in hazardous locations.
Any 500 series pumpheads not listed here are NOT suitable for use in hazardous environments (at date of issue).
3. Hazardous environments
All of Watson-Marlow's ATEX pumps are classified as Group II, Category 2 equipment under the definitions of 94/9/EC:
"Group II, Category 2 products should be designed to be capable of remaining within their operational parameters, as stated in the instruction manual, and based on a high level of protection for their intended use, in areas in which explosive atmospheres caused by mixtures of air and gases, vapours, mists or air/dust mixtures are likely to occur."
Furthermore, "The explosion protection relating to this category must function in such a way as to provide a sufficient level of safety even in the event of equipment with operating faults or in dangerous operating conditions which normally have to be taken into account".
Watson-Marlow pumps must not be used in the underground parts of mines, and in surface installations of such mines, likely to become endangered by firedamp and/or combustible dust.
NB: where two or more items of ATEX equipment are combined, the complete assembly shall carry the same rating as the lowest ranking individual piece of equipment.
4. Operating parameters
The following tube materials can be used with the 501RLA pumpheads. Bore sizes range from 0.5 to 8.0mm, with an option of 1.6 or 2.4mm wall thickness:
Tubing - working temperature range |
Marprene | 5C to 80C |
| Bioprene | 5C to 80C |
| Pumpsil | -20C to 80C |
| Sta-Pure | 0C to 80C |
| Chem-Sure | 0C to 80C |
| Neoprene | 0C to 80C |
| PVC | 0C to 80C |
The following parameters define the boundary of the safe working envelope - these values must not be exceeded (ATEX compliance will be invalidated).
501RLA pumpheads |
Operational temperature range | -20C to 80C |
| Max. peak pressure (0.5 to 4.8mm bore) | 2 bar |
| Max. peak pressure (6.4 to 8.0mm bore) | 1 bar |
| Max. continuous speed | 300 rpm |
| Max. intermittent speed | 500 rpm |
| Corrosion resistance | see Section 7 - Materials |
| Tube life | see Section 5 - Tube failure |
When two or more items of ATEX equipment are combined, the permissible operating envelope will be determined by the narrowest range after considering all values for a given parameter.
5. Potential pump hazards
As part of the requirements of 94/9/EC all potential hazards, including expected malfunctions, have been identified and subjected to a risk assessment. In order to prevent these ignition sources becoming effective a number of changes have been implemented. In addition to engineering modifications, the changes include additional operating instructions in order to specifiy correct usage in hazardous locations. Please refer to Sections 6 - 10 for further details.
Recognised ignition sources |
Surface temperatures of rollers and spindles |
| Tube burst and subsequent spilling of pumped fluid |
| Mechanical failure of rotor hub |
| Exothermic chemical reaction |
| Electrostatic discharge |
| Bearing failure |
| Spring failure |
6. Installation guidelines
Please refer to the standard 501RL manual (PB0202) for general installation instructions.
All ATEX pumpheads include provision for the prevention and dissipation of electrostatic charge. In order to dissipate electrostatic charge effectively there must be sufficent electrical contact between the pumphead and the suitably earthed drive.
It is imperative that the 501RLA pumpheads are earthed by connecting the earth terminal on the track (circled in the photograph below) to earth (usually via a suitable point on the pump drive).
It is possible to check the effectiveness of any earth connection by measuring its electrical resistance. The resistance from any point on the safeguard to the earth terminal is typically 25Ohms. To ensure reliable dissipation of static the maximum resistance to earth should not exceed 1MOhm.
7. Tube life
There are a number of factors that contribute to the life of the tubing:
Factors influencing tube life |
Normal tube fatigue - dependent on tube size and material |
| Incorrect tube loading - see 501RL manual (PB0202) for guidance |
| Excess working pressure - see Section 4 "Operating parameters" |
| Chemical incompatability - a table of tubing compatibility can be found on http://www.watson-marlow.com/wmb-gb/p-chem-a.htm. Immersion kits are available from Watson-Marlow for testing. |
For each application it is strongly recommended that tube life should be determined by trials, prior to installation in a hazardous environment. If this is not possible, or if there is any doubt in terms of tube life then the following hazards should be recognised before installing a pump in a potentially explosive atmosphere:
Chemical reaction between pumped fluid and pump materials - the materials of construction are listed in Section 9 |
| Pumped fluid can be ignited by surface temperature of rollers - all Watson Marlow's ATEX equipment has been rated as T4 (meaning that even under worst-case operating conditions the maximum surface temperature will not exceed 135C) |
8. Servicing and cleaning requirements
If aggresive liquids are spilled onto the pumphead, the head should be removed and cleaned with a mild detergent. Remove any tubing from the pumphead, and swing out the crank handle to expose the rotor retaining screw. Turn the screw anti-clockwise to release the collet and withdraw the motor from the shaft. Loosen the track locating screw and pull the track clear.
The same cleaning procedure should be used to limit the build-up of dust (which can become electrostatically charged and/or heated by friction).
The moving parts of the rotor should be checked from time to time for freedom of movement. Pivot points and rollers should be lubricated occasionally with Teflon lubricating oil.
Because of the importance of dissipating electrostatic charge the earthing lead should be regularly checked for signs of corrosion.
9. Materials of construction - 501RLA pumpheads
Description | Part No. | Material | Finish |
Rotor body | MN0496C | Zinc alloy | Chromium plating |
Rotor arm | MN0933C | Zinc alloy | Chromium plating |
Roller spindle | MN0009T | Stainless steel 303S31 | |
Lever | MN0013T | EN58BM | |
Guide spindle | MN0113T | Stainless steel 303S31 | |
Spring, rotor (1.6mm) | SG0001 | Stainless steel DIN 17224 | Blue paint |
Spring, rotor (2.4mm) | SG0002 | Stainless steel DIN 17224 | Red paint |
Collet | CL0656T | Stainless steel 303S31 | |
Roller (standard) | MN0011T | MOS2 Filled Nylon | |
Roller (Sta-Pure) | MN1275T | Stainless steel 303S31 | |
Roller, follower | MN0012T | MOS2 Filled Nylon | |
Tube clamp | MN1219M | Kematal (Acetal copolymer) | |
Tube clamp | MNA626A | Kematal (Acetal copolymer) | |
Spring, tube clamp | MN0014S | Stainless steel 301S21 | |
Guide roller | MN0164M | Kematal (Acetal copolymer) | |
Safeguard | MN1322T | Polycarbonate | Carbon paint |
Track | MN1323T | Zinc alloy | Powder coated |
Track (cc) | MN1324T | Zinc alloy | Powder coated |
Hinge | MN0266M | Kematal (Acetal copolymer) | |
Spring | MN1217T | Stainless steel DIN 17224 | |
Fastener | FN4502 | Carbon spring steel BS1449 | Nickel plating |
Screws | | Stainless steel DIN 17224 | |
Earth lead | MNA0684A | Copper | Tin coating |
The above materials have been carefully selected and have a well proven track record. However, if there are any aggressive chemicals present then it is imperative that a risk assessment is conducted. This must not be limited to just the pumped fluid but should also include any other aggressive fluids in the intended operating environment.
10. Summary of modifications
ATEX features of the 501RLA pumpheads |
Conductive coating | The safeguard has been coated with a carbon-based
paint to enable the dissipation of electrostatic charge |
| Earth strap | An earthing bond links the safeguard and the track |
| ATEX label | This is a requirement of the Directive and includes the ATEX
rating for the pumphead (Group II Category 2 for gas, T4) |
| ATEX manual | This is an addendum to the existing manual
and includes ATEX specific information |
11. ATEX marking
The 501RLA pumpheads have been marked with the following labels:
12. Replacements
Spares and replacements should be ordered through Watson-Marlow Bredel pumps or through an offical representative. Only Watson-Marlow spares and replacements should be used in order to guarentee continued compliance with the ATEX directive.
Watson-Marlow's policy is to provide spare parts for all products for a minimum of 7 years from discontinuation. The ability to implement this policy is not entirely within Watson-Marlow's control and cannot be guaranteed, but every effort will be made to honour this policy.
Watson-Marlow Bredel Pumps can be contacted at:
Watson-Marlow Bredel Pumps
Falmouth
Cornwall
TR11 4RU
England
Tel: +44 (0)1326 370370
Fax: +44 (0)1326 376009
Email: support@watson-marlow.co.uk
Web: www.watson-marlow.com
