Tank Farm

[epillow]

I need to install motors and motor starters for a tank farm, 2 tanks 8000 gal ea, which stores isopropyl alcohol. The tank farm is located outdoors as will be the motor starters (NEMA 4x). The alcohol tanks are located on a concrete pad with a 22? retaining wall around the perimeter of the pad. The two motors (3hp, 460V) will be located at the base of the tanks on a small pedestal. And the motor starters will be located outside the retaining wall. Here are my questions. 1) What division should the pump motors need to be rated (ClD1 of ClD2)? 2) How far from the retaining wall and tanks should my starters be located.

My thoughts are as follows:
Motors: ClD2 within 3ft of pumps. C1D1 between pump and wall if less than 10ft to wall.
Ref: ?Electrical Installations in Hazardous Locations? Page 74

Starters: Unclassified anywhere outside of retaining wall. Ref: ?Electrical Installations in Hazardous Locations? Page 118

Would this be correct or am I totally off base?

Thanks

View attachment 1358

 

[jatrottpe]

One approach to consider would be utilzing NFPA 497 figures 5.9.4(a) and 5.9.2(a) for classifing the area

Per NFPA 497 fig 5.9.4.a
Assuming tank is greater than 5000 gallons

A 5 ft envelope around any vents would be Class 1 Division 1
A 10 ft envelope around tanks would be Class 1 Division 2
A 10 ft envelope around the Class 1 Division 1 area would be Class 1 Division 2
From the 10 ft envelope to the retaining wall up to the retaining wall elevation would be Class 1 Division 2

In addition per fig 5.9.2a
a 15 ft radius around the pumps would be considered Class 1 Division 2.

As long as the starters are outside of these envelopes, they would not have to be Nema 7/9 rated.

 

[rbalex]

Installations within the scope of Article 515 can usually be Classified readily from Table 515.3.

 

[weressl]

I need to install motors and motor starters for a tank farm, 2 tanks 8000 gal ea, which stores isopropyl alcohol. The tank farm is located outdoors as will be the motor starters (NEMA 4x). The alcohol tanks are located on a concrete pad with a 22? retaining wall around the perimeter of the pad. The two motors (3hp, 460V) will be located at the base of the tanks on a small pedestal. And the motor starters will be located outside the retaining wall. Here are my questions. 1) What division should the pump motors need to be rated (ClD1 of ClD2)? 2) How far from the retaining wall and tanks should my starters be located.

My thoughts are as follows:
Motors: ClD2 within 3ft of pumps. C1D1 between pump and wall if less than 10ft to wall.
Ref: ?Electrical Installations in Hazardous Locations? Page 74

Starters: Unclassified anywhere outside of retaining wall. Ref: ?Electrical Installations in Hazardous Locations? Page 118

Would this be correct or am I totally off base?

Thanks

View attachment 1358

You should request that the Owner provide you with an area classification drawing and perform the selection of equipment and installation accordingly. It is an OSHA requirement - on top of NEC - and if you install something without proper documentation as the basis of your work, you can be held liable in the future.

The area classification drawing should show you the extent of each Class/Division, both vertically an horizontally, list the chemical involved with their Group definition and T-rating.