通用NTEP认证测试流程.docVIP

Shock Overload Test Procedure Purpose Verify shock overload protection of scale under test. Required Equipment Cardboard box with a cross-sectional area up to ? the area of the platform to be tested. Box to be completely filled with sand. Weight of box shall be ? the capacity of the scale. Scale platform to be tested. Procedure Zero the scale. Drop box onto platform, 9 times total, in positions and order shown below (Figure 1), at a distance of 6 inches from the platform. The indicated weight shall not exceed +/-2% of scale capacity. Scale cannot be zeroed before reading is taken. Figure 1 Drop Order and Positions Figure 2 Test Layout Increasing / Decreasing Load Test Procedure HB44 N1.1., N1.2., T.N.3.2. Purpose Discover linearity and hysteresis characteristics of the scale. Hysteresis - The maximum allowable difference between weight readings for the same applied load; one reading obtained by increasing the load from zero to scale capacity and the other by decreasing the load from scale capacity. Linearity - The deviation of the indicated weight from a straight line drawn between no load and scale capacity, as measured on increasing load only. Required Equipment Test weights Procedure Apply weight to scale in order shown in table and record displayed weight. Test up to maximum division level required for NTEP accuracy. Weight Applied (d) Test Weight Allowable Error (+/-d) Test Result 0 0.5 50 0.5 500 0.5 1000 1.0 1500 1.0 2000 1.0 2500 1.5 3000 1.5 3500 1.5 4000 1.5 4500 2.5 5000 2.5 4500 2.5 4000 1.5 3500 1.5 3000 1.5 2500 1.5 2000 1.0 1000 1.0 500 0.5 50 0.5 0 0.5 Repeatability Test Procedure HB44 T.N.5. Purpose Discover repeatability characteristics of the scale. Repeatability - The difference between scale readings at repeated loads under identical loading and environmental conditions. Required Equipment Test weights Procedure Place ? of scale capacity on platform and record