scope:

This Standard specifies the performance requirements for hermetically sealed, flush mounting, moving coil instruments having nominal barrel diameters of 26 mm and 38 rom, with exposed rear connecting terminals. Instruments to this Standard are not fitted with an external mechanical zero adjuster. Instruments to this Standard, but having arbitrary scales and other markings, are also acceptable subject to "such instruments "meeting the conditions of sub clause 6.15.

In accordance with international practice the Class Index system adopted in BS 89: 1977(IEC 51) is used in this specification. Reference should be made to BS 89: 1977(IEC 51), particularly the Foreword and Appendices for more precise information on this system. For specific information concerning the particular class indices adopted, see Table F on page 18 of this Defence Standard.

When it is desired to use a range of instruments or to indicate by electrical means quantities not specifically covered by the relevant PART of this Standard, a manufacturer or a design authority may request that such items be considered for inclusion in this document. In such instances, details of dial markings and any special requirements together with the appropriate drawings, shall be submitted to the Qualification Approval Authority.