【正文】 b) 40 to 250 size safety pattern gauges with a baffle wall (designated by S3, see clause 12). All types of safety pattern gauges shall meet the requirements defined in , , and . Safety pattern gauges with baffle wall shall additionally meet the requirements defined in . Energy release test Pressure gauges shall pass the energy release test defined in , which simulates the failure of a pressureresponsive element and the release of high energy gas into the case. Window The window shall be of nonsplintering material, such as laminated glass or nonsplintering plastic. Blowout back A blowout back shall be fitted. The blowout back shall be resistant to blocking by debris and dirt and shall operate at a pressure of not more than half of the window burst pressure and not more than 1,5 bar. Test as given in . The area of blowout back shall be as large as is practicable. NOTE. For safety pattern gauges without a baffle wall, a blowout device according to is sufficient. Baffle wall The baffle wall shall form a permanently fixed structural part of the case interposed between the Bourdon tube and the dial. The number and size of holes in the baffle wall shall be kept to a minimum consistent with fixing screws, pointer shaft and dial pillars and shall not exceed 5 % of the area of the baffle wall. Marking 40 to 80 size safety pattern gauges without baffle wall (designated by S2) shall have dials marked S and with the EN number of this standard. 40 to 250 size safety pattern gauges with baffle wall (designated by S3) shall have dials marked S and with the EN number of this standard. Gauges for use with oxygen or acetylene The gauges shall be of safety pattern type. All materials liable to e into contact with oxygen or acetylene shall ply with EN 29539. Gauges for use with oxygen Bourdon tubes and other parts in contact with the gas shall be free of oil and grease. Only lubricants suitable for use in oxygen at maximum working pressure shall be used. The dial shall。 BSI 1998 Page 11 EN 8371 : 1996 Table 16. Symbols for types of pressure elements Type of Bourdon tube Symbol Circular Spiral Coiled The scale spacing shall not be smaller than 1 mm. The scale spacing shall be as constant as possible. The difference between the longest and shortest spacing shall not exceed 1/5 of the latter. Scale numbering Scale numbering will be at the manufacturer39。 208。 208。 120 120 120 60 60 60 60 60 60 60 60 60 208。 208。 208。 30 30 30 30 30 30 30 30 30 30 80 100 150 and 160 250 208。 208。 208。 208。 208。 208。 208。 40 208。 208。 200 200 208。 400 208。 208。 208。 208。 208。 208。 208。 0 to 400 40 50 63 208。 208。 208。 125 125 125 50 50 50 50 50 50 50 50 50 208。 208。 208。 25 25 25 25 25 25 25 25 25 25 80 100 150 and 160 250 208。 208。 208。 208。 208。 208。 208。 32 208。 208。 160 320 208。 320 208。 208。 208。 208。 208。 208。 208。 0 to 160 40 50 63 208。 208。 208。 100 100 100 50 50 50 50 50 50 50 50 50 208。 208。 208。 20 20 20 20 20 20 20 20 20 20 80 100 150 and 160 250 208。 208。 208。 208。 208。 208。 scan rate 1 octave per minute for the period of 2 h per axis. The change of indication after the vibration test shall not exceed 0,5 times class. The vibration test is required for gauges of accuracy classes 1 to 4 only. BSI 1998 Page 10 EN 8371 : 1996 Leak rate The leak rate shall not exceed 5 3 1023 mbar 180。 range of frequency from 10 Hz to 150 Hz。 acceleration 5 m/s2。 177。 0,25 and 0,6. Operating conditions Rated temperatures in service Ambient temperature and temperature of the fluid under pressure: 220 8C to + 60 8C Minimum and maximum temperature in service for liquidfilled gauges shall be in accordance with the liquid properties. Rated storage temperature Storage temperature: 240 8C to +70 8C. The gauge shall not change its appearance. The dial and pointer shall not crack, blister or change colour. Protection against ingress of water and foreign particles (degree of protection) Remended minimum protection ratings in accordance with EN 60529: 177。s data. d1 Outside diameter of case d2 Outside diameter of flange d3 Diameter of fixing hole circle d4 Diameter of fixing holes Figure 1 Page 5 EN 8371 : 1996 BSI 1998 Table 5. Dimensions for high pressure shank Dimensions in millimetres Thread size d1 d2 0,1 d3 d4 d5 0 20,3 l1 0 20,3 l2 0 20,3 G 1/2 B (for HP) 7,14 15 17,5 19 25 22 Table 4. Dimensions of parallel threaded shanks Dimensions in millimetres Thread size d1 d2 d3 d4 min. l1 +0,5 0 l2 l3 +0,5 0 f w min. G 1/8 B 4 8 8 10 2 2 1,6 8 G 1/4 B 5 9,5 9,5 13 2 2 2 10 G 3/8 B 5,5 13 13 16 3 3 2 13 G 1/2 B 6 17,5 17,5 20 3 3 3 17 NOTE 1. For stainless steel screwed connection, f dimensions can be raised up to 50 %. NOTE 2. G 1/8 B may be made without spigot. NOTE 3. G 1/8 B may be made without groove f. In this case, the length of threading shall be equal to l1. NOTE 4. For inchangeability with previous standards, the spigot of G 1/4 B can be manufactured with diameter 4 mm. Screw threads Parallel pipe threads (symbol G) according to ISO 2281. Taper pipe threads (symbol NPT) according to ANSI/ASME . Other threads specific to certain industries are acceptable. Shanks with parallel pipe threads High pressure shank