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Accessories - Steam Syphons

Machine Threads

For Shafts on Plain, Syphon and "RSP" Models, Machine Threads (American Standard Screw Threads) are recommended for the rotating shaft of all Rotary Union® joints for applications involving speeds of 600 rpm or more.
When Machine Threads are desired, they must be specified when ordering the Rotary Union® joint. Be sure to specify either right-hand or left-hand rotation of the drum or cylinder.
Machine Threads for standard-model Rotary Union® joints are indicated in the specification data presented in this catalog. The condensed reference table below consolidates Machine Threads information for various Rotary Union® joint nominal sizes. Copper shaft gaskets are normally furnished with machine thread joints.

How to Order Machine Threads
When Machine Threads are desired on the rotating shaft of a Rotary Union® joint, be sure to include the following information with your order:

  • Rotating shaft shall be supplied with Machine Threads (American Standard Screw Threads).
  • Exact size of Machine Threads preferred, when choice is given (examples: 7/8-14, 7/8-16, etc.).
  • Left-hand or right-hand Machine Threads depending on clockwise or counterclockwise rotation of machinery.
Note: For clarity, include both the machine rotation as viewed from machine journal and the shaft thread direction.

Machining Detail
For Fabricating Syphon Pipe for "RSP" Models
Revolving syphon/supply pipe is not normally supplied with Type "RSP" Rotary Union® joints. The internal, rotating pipe can be easily fashioned from standard tubing or pipe, following the accompanying machining tolerances for the given size of syphon. See individual Type "RSP" joint specifications for recommended syphon size.

Nominal
Shaft
Outlet
A
Shaft
Diameter
American Standard Screw Thread
Thread
Diameter
Threads
Per Inch
Thread
Length L
1/4" 3/4" 5/8" 18 7/16"
3/8" 3/4" 5/8" 18 7/16"
1/2" 1 1/8" 3/4" or 7/8" 16 or 14 5/8"
3/4" 1 1/4" 1" 14 3/4"
1" 1 1/2" 1 1/4" 12 7/8"
1 1/4" 1 7/8" 1 5/8" 8 or 12 7/8"
1 1/2" 2 1/4" 2" 8 or 12 1 1/8"
2" 2 7/8" 2 1/2" 8 or 12 1 5/16"
2 1/2" 3 1/2" 3" 8 or 12 1 9/16"
3" 4 1/8" 3 1/2" 8 or 12 1 3/4"
Note
for additional information, see selection data of specific Rotary Union joint required or consult factory.

Nominal
Syphon
Size*
Finished
Diameter
M
Minimum
Length
N
1/4"
tubing
.252" 1 5/8"
.249"
1/4" .528" 1 3/4"
.522"
3/8" .663" 2"
.657"
1/2" .809" 3"
.803"
3/4" .997" 3 1/4"
.991"
1" 1.247" 3 3/4"
1.241"
1 1/4" 1.621" 4 1/4"
1.615"
1 1/2" 1.871" 4 1/4"
1.865"
2" 2.308" 4 1/4"
2.302"
2 1/2" 2.807" 4 1/4"
2.801"
3" 3.432" 5 1/8"
3.426"