Watlow Heater Catalog

Reference Data

Tubular Elements and Assembly Selection Guide

Circulation Heater Size

Free Cross Sectional Area in Square Feet (Number of Elements in Parenthesis)

Free Cross Sectional Area of WATROD and FIREBAR Circulation Heaters Free cross sectional areas from the chart are in square feet. Calculations are based on: • Flange 12 inches and under, pipes are schedule 40 • Flanges 14 inches and above, pipes are standard wall thickness 0.375 in. (9.5 mm) • All WATROD heating elements are 0.475 in. (12 mm) diameter

in.

WATROD 2 1 / 2 NPT 3 Flange 4 Flange 5 Flange 6 Flange 8 Flange

0.044 0.044 0.074 0.124

(3) (3) (6) (6)

0.037

(6)

0.117 0.164 0.296 0.460 0.652 0.781 1.054

(9)

0.172 (12) 0.303 (18)

(15) (21) (36) (54) (72) (87)

0.288

(24)

10 Flange 0.481 (27) 12 Flange 0.697 (36) 14 Flange 0.848 (45) 16 Flange 1.091 (72) 18 Flange 1.372 (102) 20 Flange 1.748 (108)

1.017 (102) 1.342 (114) 1.704 (126)

1.357 (108) 1.733 (114)

FIREBAR 2 1 / 2 NPT

0.0417 (3)

549