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Brookfield AMETEK

Powdered Milk

Powder Flow Application Data Sheet

USE

Mixing with water creates a cheaper alternative to buying regular milk.

Test Equipment

  • Instrument: Powder Flow Tester (PFT)
  • Trough: 230 cc, 6-inch diameter
  • Lid Type: Vane Lid, 304 s/s, 33cc, 6-inch diameter (Flow Function)
    Wall Lid, 304 s/s, 2B finish, 6-inch diameter (Wall Friction)
  • Type of Test: Flow Function Test, Wall Friction Test
  • Temperature: Room Temperature (70-72° F)
  • Humidity: 25.4%

Method

A Brookfield Powder Flow Tester, equipped with Powder Flow Pro software for automated instrument control and data acquisition, was used to test this name brand powdered milk. The powdered milk was scooped into the trough, and the scraping tool was then used to evenly distribute the powder throughout the trough. After recording the sample weight and entering it into the software, a standard flow function test and then a wall friction test were run. Time required for each test was 35 minutes and 20 minutes respectively.

Parameters Measured

  • Flowability: Easy Flowing
  • Wall Friction: 10
  • Bulk Density: 335 kg/m (fill density) to 385 kg/m (9.5 kPa)

Analysis

  • Hopper Shape: Conical
  • Arching Flow Factor: 1.40
  • Critical Arching Dimension:°.464in (11.6mm)
  • Rathole Diameter: Dependent on bin diameter

Results


Figure 1: Powdered Milk Flow Function Graph

Figure 1 shows the flowability of the powdered milk at different levels of consolidating stress. These results show that the powdered milk is generally free flowing throughout all levels of consolidating stress.


Figure 2: Powdered Milk Wall Friction Graph

Figure 2 represents the angles of wall friction at different levels of normal stress. Angles of wall friction represent the friction between the sliding powder and the wall of the hopper or chute at the onset of flow. In this test a stainless steel lid was used, illustrating what the friction would be like if the powdered milk was in a stainless steel hopper. At all levels of consolidating stress, the powdered milk exhibits an effective angle of wall friction of about 10.


Figure 3: Powdered Milk Bulk Density Graph

Figure 3 shows the bulk density of the material at different levels of consolidating stress. This graph tells us that the powdered milk has a fill density of about 335 kg/m and rises to about 385 kg/m at around 4.5 kPa of consolidating stress. In general, a free flowing powder will show very small changes in bulk density, whilst a cohesive or poor flowing powder will generally show a large increase in bulk density.

Conclusion

The powdered milk is an easy flowing powder throughout all consolidation stress levels. This powder should not exhibit many flowability problems. The critical arching dimension, of°.464 inches (11.6 mm) provides a conservative estimate to prevent arching from happening, provided the minimum outlet dimension of the hopper exceeds this value. The critical ratholing dimension is dependent on the diameter of the bin. Powder Flow Pro can automatically calculate the rathole diameter once the bin diameter is entered.