1.6.4.2 Marking
An example of ATEX equipment marking is shown below. The actual classification of the pump will be engraved on the nameplate.
II 2 GD c IIC 135 ºC (T4)
Equipment Group
I = Mining
II =
Category
2 or M2 = High level protection
3 = normal level of protection
Gas and/or Dust
G = Gas; D= Dust
c = Constructional safety
(in accordance with EN
Gas Group (Equipment Category 2 only)
IIA – Propane (typical)
IIB – Ethylene (typical)
IIC – Hydrogen (typical)
Maximum surface temperature (Temperature Class) (see section 1.6.4.3)
1.6.4.3 Avoiding excessive surface temperatures
ENSURE THE EQUIPMENT TEMPERATURE CLASS IS SUITABLE FOR THE HAZARD ZONE
Pumps have a temperature class as stated in the ATEX Ex rating on the nameplate. These are based on a maximum ambient of 40 °C (104 °F); refer to Flowserve for higher ambient temperatures.
The surface temperature on the pump is influenced by the temperature of the liquid handled. The maximum permissible liquid temperature depends on the temperature class and must not exceed the values in the table that follows.
The temperature rise at the seals, bearings and due to the minimum permitted flow rate is taken into account in the temperatures stated.
| Maximum | Temperature limit of liquid | |
Temperature | handled (* depending on | ||
surface | |||
class to | material and construction | ||
temperature | |||
EN | variant - check which is | ||
permitted | |||
| lower) | ||
|
| ||
|
|
| |
T6 | 85 °C (185 °F) | Consult Flowserve | |
T5 | 100 °C (212 °F) | Consult Flowserve | |
T4 | 135 °C (275 °F) | 115 °C (239 °F) * | |
T3 | 200 °C (392 °F) | 180 °C (356 °F) * | |
T2 | 300 °C (572 °F) | 275 °C (527 °F) * | |
T1 | 450 °C (842 °F) | 400 °C (752 °F) * | |
|
|
|
The responsibility for compliance with the specified maximum liquid temperature is with the plant operator.
Temperature classification “Tx” is used when the liquid temperature varies and the pump could be installed in different hazardous atmospheres. In this case the user is responsible for ensuring that the pump surface temperature does not exceed that permitted in the particular hazardous atmosphere.
If an explosive atmosphere exists during the installation, do not attempt to check the direction of rotation by starting the pump unfilled. Even a short run time may give a high temperature resulting from contact between rotating and stationary components. Furthermore, confinement of liquid in the pump and pipes must be avoided (valve closed). If the liquid heats up this may cause excessive pressure and lead to bursting of pump components.
Where there is any risk of the pump being run against a closed valve generating high liquid and casing external surface temperatures it is recommended that users fit an external surface temperature protection device.
Avoid mechanical, hydraulic or electrical overload by using motor overload trips, temperature monitor or a power monitor and make routine vibration monitoring checks.
In dirty or dusty environments, regular checks must be made and dirt removed from areas around close clearances, bearing housings and motors.
1.6.4.4Preventing the build up of explosive mixtures
ENSURE PUMP IS PROPERLY FILLED AND VENTED AND DOES NOT RUN DRY.
Ensure pump and relevant suction and discharge pipeline system is totally filled with liquid at all times during the pump operation, so that an explosive atmosphere is prevented. In addition it is essential to make sure that seal chambers, auxiliary shaft seal systems and any heating and cooling systems are properly filled.
If the operation of the system cannot avoid this condition the fitting of an appropriate dry run protection device is recommended (eg liquid detection or power monitor).
To avoid potential hazards from fugitive emissions of vapor or gas to atmosphere the surrounding area must be well ventilated.
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