Howell Labs: Home

Howell Laboratories, Inc.
P. O. Box 389, 188 Harrison Rd., Bridgton Maine 04009 USA
(207) 647-3327 (888) 744-8359 FAX (207) 647-8273 contracts@howelllabs.com

- An Employee-Owned Company -
Certified to ISO 9001:2000

Replacing Model 4737 Desiccant Dehydrator with Model 6995 Membrane Dehydrator


Aboard USS Yorktown (CG48)
4737 at left, 6995 at right - smaller, lighter,
more dependable, more efficient ...

Installation Instructions

  1. Remove the existing Model 4737 type II dehydrator.
  2. Drop in the Model 6995 membrane dehydrator. The base footprint, air inlet and outlet, and drain connection are all identical to the 4737's.
  3. Connect 115 VAC to the electrical panel terminals. Installation is complete.

Simplified Operating Instructions

  1. Close all three of the main flowmeter ball valves.
  2. Check the alignment of the valves on the instrument panel. Make sure that all three are pointed up.
  3. Switch AC power on. The power-on lamp should light. The humidity alarm lamp will probably light.
  4. Open the inlet air shutoff valve, external to the unit. Make sure that air pressure is between 80 and 150 psig.
  5. Check purge flow. It should be between 15 and 18 scfm (Marks I and IA) or 16 to 20 scfm (Mark II). Troubleshoot per the Technical Manual if purge flow is not within specs.
  6. Check the calibration flowmeter to be sure its valve is closed.
  7. Let the unit operate with purge flow only until the humidity alarm shuts off. This may take up to an hour or so, depending on how long the unit has set since last use.
  8. After the humidity alarm goes off, open the flowmeter isolation valves. Make sure that flow does not exceed 30 scfm.
Last updated: 03/18/2008
Webmaster: Al Friend
© 2001-2008 Howell Laboratories, Inc. All rights reserved.
 Printable Adobe Acrobat version
Get Acrobat Reader (free download)