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3 | Explosion protection

D-LX 201/721

Temperature classes

For North American explosion protection, classification into temperature classes is

performed similarly to the procedure outlined in section 3.4 Temperature classes [}18].

The maximum surface temperature is classified into Classes T1 to T6, in accordance

with NEC 500. This classification corresponds to the ATEX temperature classes, but

does have additional sub-groups (e.g. T2A, T2B etc.). The temperature classes spe-

cified on the type label for the permissible ambient temperature ranges must always

be complied with in order to guarantee the explosion protection.

Zone classification and housing protection classes

Classification into zones (as per the ATEX guidelines) has been omitted as per

NEC500.

The housing protection class is described in accordance with NEMA (National Elec-

trical Manufacturing Association). The NEMA protection classes are not directly com-

parable with the European IP protection classes. The grading is based on different en-

vironmental influences and criteria in the relevant guidelines.

The requirements for the flame monitor housings in terms of protection against dam-

age caused by internal explosions are met through design-based measures. The se-

lection of suitable components also ensures that there is no possibility of incidents oc-

curring in normal operating conditions as a result of sparks either in or on the housing.

Labelling as per NEC 500

Housing Labelling as per NEC 500 Ambient temperature

Class I, Div. 1, Group A, B, C, D, T5 -40 °C (-40 °F) <= Ta <= +85 °C (185°F)

Class I, Div. 1, Group A, B, C, D, T6 -40 °C (-40 °F) <= Ta <= +70 °C (158 °F)

Class II, Div. 1, Group E, F, G, T5; Class III -40 °C (-40 °F) <= Ta <= +85 °C (185°F)

Class II, Div. 1, Group E, F, G, T6; Class III -40 °C (-40 °F) <= Ta <= +70 °C (158 °F)

Class I, Div. 2, Group A, B, C, D, T4 -40 °C (-40 °F) <= Ta <= +65 °C (149 °F)

Class I, Div. 2, Group A, B, C, D, T6 -40 °C (-40 °F) <= Ta <= +40 °C (104 °F)

Class II, Div. 2, Group E, F, G, T4; Class III -40 °C (-40 °F) <= Ta <= +65 °C (149 °F)

Class II, Div. 2, Group E, F, G, T6; Class III -40 °C (-40 °F) <= Ta <= +40 °C (104 °F)

3.8 Ex type label

Flame monitors designed for operation in hazardous areas also have an Ex type label

. The approval for use in hazardous areas is only valid in connection with the corres-

ponding labelling on the Ex type label of the flame monitor. Only those flame monitors

with the corresponding labelling may be used in a potentially explosive environment.

DURAG D-LX 201 User Manual

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