CG-47 CLASS ADVISORY NO. 01-85A
(ADDENDUM ONE) (UNCLASSIFIED)
PRAIRIE/MASKER AIR SYSTEM FLOW
OPERATIONAL GUIDANCE
COMNAVSEASYSCOM WASHINGTON DC MSG 210136Z DEC 85
REF: A. COMNAVSEASYSCOM WASHINGTON DC 251311Z JUN 85, CG-47
CLASS ADVISORY C001-85 (CONF)
1. THE PURPOSE OF THIS CG-47 CLASS ADVISORY, ADDENDUM ONE IS TO
PROVIDE FURTHER GUIDANCE ON OPERATING THE PRAIRIE/MASKER SYSTEM.
2. PRAIRIE/MASKER AIR FLOW IS RESTRICTED BY MARINE GROWTH AND SILT
WATER EMULSION. IN ORDER TO REDUCE THE SILT WATER EMULSION PROB-
LEM, SECURE THE PRAIRIE/MASKER SYSTEM PRIOR TO ENTERING PORT, SHAL-
LOW WATERS, OR SILT LADEN WATERS. IF THE PRAIRIE/MASKER SYSTEM IS
SECURED AFTER ENTERING SILT LADEN WATERS, WATER AND SILT WILL ENTER
THE PRAIRIE/MASKER BELTS AS THE PRAIRIE/MASKER AIR PRESSURE DROPS TO
ZERO.
3. NAVSEA IS DEVELOPING A TECHNICAL MANUAL FOR PRAIRIE/MASKER
OPERATION. UNTIL ISSUANCE OF THE TECHNICAL MANUAL INTERIM GUIDANCE
ON MASKER OPERATION IS PROVIDED:
A. MASKER REGULATOR VALVES HAVE DIFFICULTY REGULATING PRES-
SURE TO THE BELTS AT LOW FLOW RATES AND BECOME AGGRAVATED AS THE
BELTS BECOME CLOGGED. THE RESULTING VALVE OSCILLATION MAY VARY
THE MASKER FLOWS SUFFICIENTLY TO BE DETECTED BY OVER-THE-SIDE NOISE
SURVEYS. FOR VALVES THAT FLUCTUATE IN EXCESS OF PLUS OR MINUS 5 PSIG,
SHIPS SHOULD SECURE THE REGULATOR VALVE AND OPERATE THE SYSTEM
WITH THE BYPASS VALVE THROTTLED TO MAINTAIN A MASKER SUPPLY PRES-
SURE CONSISTENT WITH PARAGRAPH 2A OF REFERENCE A.
B. AFTER BELTS HAVE BEEN CLEANED, EACH EMITTER BELT GLOBE
VALVE SHOULD BE THROTTLED TO OBTAIN THE FLOW RATES LISTED IN REFER-
ENCE A. NOTE THAT THE FLOWMETERS SHOULD BE WORKING AND
CALIBRATED AND USED ONLY TO ESTABLISH AND BALANCE THE FLOW RATES
AND FOR PERIODIC CHECKS. ENSURE THAT THE FLOWMETERS ARE SECURED
DURING NORMAL MASKER OPERATION TO PREVENT DAMAGE DUE TO CLOGG-
ING AND CORROSION. ONCE BELTS ARE CLEANED AND NORMAL FLOW RATES
ARE RE-ESTABLISHED, AUTOMATIC REGULATION MAY POSSIBLY BE RESUMED
BY OPENING THE MASKER REGULATOR CUT OUT VALVES AND SECURING THE
BYPASS VALVE. REGULATOR VALVE BINDING MAY PRECLUDE THIS AND RE-
QUIRE CONTINUED BYPASS OPERATION.
4. NAVSEA IS DEVELOPING TECHNICAL PROCEDURES FOR CLEANING AND
HYDROBLASTING THE PRAIRIE/MASKER SYSTEM.
CG-47