194 



GREENHOUSE AND WINDOW-GARDEN WORK 



Size of pipes connecting radiating surface and the boiler or heater. 



Various empirical rules have been given for proportioning main- 

 supply and return pipes, which have proved quite satisfactory in 

 practice. George A. Babcock gives the following rule, which will be 

 found very satisfactory for greenhouse heating, whether with low- 

 pressure steam or with water : 



The diameter of main pipe leading to the radiating surface should 

 be equal in inches to 0.1 the square root of radiating surface in 

 square feet. The main pipes should not be less than 1| inches in 

 diameter, return pipes for water heating the same size as mains, and, 

 for steam heating, one size less than mains, but never loss than f inch 

 in diameter. The following table shows the radiating surface sup- 

 plied by various sizes of main pipe. 



(-B) SIZE OP PIPES RADIATING SURFACE SUPPLIED 



1J4 inches 155 square feet 



1% inches 225 square feet 



2 inches 400 square feet 



2^ inches 620 square feet 



3 inches 900 square feet 



3J^ inches 1220 square feet 



4 inches 1600 square feet 



(C) Table of dimensions of standard wrought-iron pipe For steam 

 and water 



1 inch and below, butt-welded ; proved to 300 pounds per square inch, hydraulic 

 pressure. 



1^ inch and above, lap- welded ; proved to 500 pounds per square inch, hy- 

 draulic pressure. 



TABLE OF STANDARD SIZES 



