273x28.58mm無縫管子 DN250/DN200/DN400/DN40/DN125

5. Apparatus

5.1 Specimen Carrier, provided with two conical supports

for locating the specimen. The test length (that is, the distance

between the point of contact of the specimen with one support

and the point ofcontact ofthe specimen with the other support)

shall be known to within 60.005 in. (0.13 mm), and the line of

plane passing through the points of contact shall be horizontal.

The specimen carrier and supports shall hold the specimen

without constraint so that the curvature, due to its def l ection,

will follow a vertical plane passing through the line joining the

points of contact between specimen and supports. Suitable

means shall be used to ensure test length.

5.2 Micrometer—traveling microscope, or equivalent

device, so connected to the specimen carrier that expansion

during heating of the carrier or connecting parts will not cause

appreciable displacement of the measuring device with respect

to the supports.

5.3 Bath—A stirred liquid bath or uniformly heated enclo-

sure in which the specimen carrier, together with adjustable

electric heating source is placed. The specimen needs to be

maintained at the desired temperatures, with a variation in

temperature throughout the gage length of the specimen not to

exceed 0.5 % of the temperature range used in the test.

5.4 Temperature Measuring Apparatus, of such accuracy

that the individual temperatures shall be known to within

60.5°F (0.3°C).

5.5 Def l ection Index—Means shall be provided for measur-

ing the def l ection of the specimen at a point midway between

the points ofsupport and along the vertical line intersecting the

line joining the points of support. Such means may comprise a

transmission rod disposed with its axis vertical and terminating

in a point or knife-edge, which shall engage the specimen

midway between the points of contact with the supports.

5.5.1 The transmission rod shall be mounted in such a

manner that it is free to move in the direction of its axis. The

rod shall bear at its free end an index suitable for microscopical

observation, or else an electrical contact with which a microm-

eter will permit the changes of the def l ection of specimen to be

accurately observed. Alternatively, the def l ection of the mid-

point of the specimen may be directly observed by optical

means whose line of sight is horizontal and passes through the

vertical line through the midpoint of the specimen. A microm-

eter screw with extended spindle making direct contact with

the specimen may be used. In this case, electrical means shall

be provided that will indicate contact without signif i cant

disturbance of the specimen. The measurement of the position

of the midpoint of the test specimen shall be of such accuracy

that the individual positions at the test temperatures shall be

known to within 60.0002 in. (0.005 mm).

5.5.2 If a transmission rod is used, it and any attached parts

shall be ofsuch weight or so counterweighted that they will not

cause a def l ection greater than 1 % of the maximum to be

produced by the action of the thermostat metal alone. When

free, the thermostat metal assumed very nearly a circular

curvature. Concentrated loading at the center of the specimen

will cause the curvature to be other than circular and may cause

signif i cant errors in the evaluation of f l exivity. The location of

the line passing through the points of contact between speci-

men and supports shall be known, with reference to the scale of

the micrometer, to within 60.002 in. (0.05 mm).

5.6 All metallic components of the f l exivity apparatus

should be made of very low coefficient of thermal expansion

components. The recommended material is Invar. 3