Principle of a vertical falling film is used to clean contaminated large diameter and length liquid oxygen /LOX/ cylindrical ducting. The cleaning cycle is performed by flowing trichloroethylene in a falling film down a vertically mounted duct for approximately one hour

Paul, H. I.

English

NASA Technical Reports Server

August 1967	 Brief 67-10299 
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Liquid Oxygen. Ducting Cleaned by Falling Film Method 
Spray Head	 Weir Cover Plate 
Flow Straightener 
Plate 
Clean Dry 	
-D \II \\ Weir Drain Nitrogen
Ov I' 
Weir Cleaning I 
Head Reservoir LLiquid Film-.-
Clean Trichloroethylene
Lox 
Suction—
I	 I 
118 lnches—j. 
From Storage Duct
Approx. 45 ft.* 
Trichloroethylene Pump 
Nitrogen to Atmospheric 
Vent System Duct Support 
& Drain Plate 
Contaminated Trichthyl 4-Sample Line 
To Redistillation Area
The problem: 
To clean contaminated large diameter and length 
liquid oxygen (LOX) cylindrical ducting with a small 
capital facility investment and at economical flow-
rates. 
The solution: 
A facility that cleans such ducting at relatively low 
cost, using the principle of a vertical falling film. 
How it's done: 
The duct is vertically mounted on a support plate as
illustrated, the support plate including a 5-inch diam-
eter drain hole to prevent liquid buildup in the bottom 
of the duct during the cleaning operation. An over-
flow weir cleaning head reservoir is bolted and 
gasketed to the duct top flange and contains a perfo-
rated flow straightening plate to remove vorticity com-
ponents in the solvent, plus a spray head required to 
clean the internal triaxial gimbal surfaces at the top 
and bottom of the duct. A solvent supply and redistil-
lation unit with a pump capable of delivering 70 gpm, 
plus a 100 psig dry nitrogen supply, and appropriate 
piping and valves complete the cleaning facility. 
(continued overleaf) 
This document was prepared under the sponsorship of the National 	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States 	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States
	 will be free from privately Owned rights. 
https://ntrs.nasa.gov/search.jsp?R=19670000299 2020-03-11T20:41:36+00:00Z
The cleaning cycle is performed by flowing 30 to 
70 gpm specification grade trichloroethylene (100 
micron maximum particle size) in a falling film down 
the duct for approximately one hour. Temperature of 
the solvent is increased during the latter part of the 
cleaning cycle to facilitate subsequent drying. Follow-
ing cleaning, the duct is purged with clean, dry nitro-
gen until all residual solvent is removed. The duct 
interior is at atmospheric pressure throughout clean-
ing and drying. 
Notes: 
I. The falling film principle may be used as an eco-
nomical way to clean straight, large diameter and 
length cylindrical piping or ducting of many ma-
terials. Multiple solvents, pickling solutions, 
alkaline cleaners, etc, may be used sequentially
with common plumbing and overflow cleaning weir 
reservoir. 
Inquiries concerning this invention may be di-
rected to:
Technology Utilization Officer 
Marshall Space Flight Center 
Huntsville, Alabama 35812 
Reference: B67-10299 
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to NASA, Code 
GP, Washington, D.C. 20546.
Source: Henry I. Paul
of The Boeing Company.
under contract to

Marshall Space Flight Center

(M FS- 1 1816) 
Brief 67-10299	 Category 03


Liquid oxygen dicting cleaned by falling film method

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