the hydrodynamics of existing sampling devices. 



More than one modular form has been described for sensing a 

 given characteristic of the water. The basis of separation has been 

 use. It would be desirable if several of these could be combined at 

 no extra cost. If a decided cost advantage would result by dividing 

 the range of capability of a module still further, the Bureau should 

 be consulted. 



It may be desirable from the manufacturer's standpoint to com- 

 bine several sensors into one module -- such as the dissolved gas 

 sensors (Section 1. 1160). It will not be mandatory to use separate 

 modules for each sensor providing it can be demonstrated to be to 

 the Bureau's advantage to combine them. 



The effect of one environmental factor on the sensor of another 

 can be significant. The effect of depth is the most pronounced since 

 it may subtly affect the operation of the electronic components, as 

 well as the sensing element. (See pages 32-35.) In general, sensors 

 should be self-compensating. 



It is suggested that a manufacturer having a capability for making 

 a product very similar to one that appears on the list contact the 

 Bureau to determine a group with which he can work, and the extent 

 and nature of support he can expect without impairing his right to 

 patent. 



The Bureau buys what is available and makes what is not availa- 

 ble and will work with Industry to build a more serviceable instru- 

 ment. 



The following general requiremients are applicable to most of 

 these instruments and instrument systems. They must: 



1. Operate in severe environments, particularly ones of high 

 humidity and salt corrosion and withstand storage tempera- 

 tures of from -Z5 to 60° C. ; 



2. Resist vibration and shock; 



3. Have high reliability and long life; 



4. Provide for accurate calibration on board ship; 



414 



