CG-47

                        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.