STUDIES ON MANAGING FLEXIBLE CONTAINERS
S. Ya. Davydov,
F. L. Kapustin,
I. D. Kashcheev,
and A. G. Ustinova
Translated from Novye Ogneupory, No. 4, pp. 24 – 26, March, 2007.
Original article submitted January 27, 2007.
Technical characteristics are given for polypropylene bags that can be used for pneumatic mining, together
with a list of standard devices for the mechanical unpacking of loose materials from soft containers. Descrip
tions are given of the design, operation, and test results for an experimental system for handling a flexible con
tainer containing a dust-forming material. An industrial equipment is proposed for handling a flexible con
tainer, tipping it, and transporting loose materials in it.
Use is steadily increasing of flexible (soft) containers for
packing dusty and powder materials, particularly for hand-
ling small batches. The advantage of a flexible container is
obvious, since it has low mass, is compact in the collapsed
state, prevents the extensive fractionation of a loose material,
and provides for return in compact form to the supplier or
producer and so on. A flexible container can be prepared as a
grade MKR soft container made of UV-stabilized polypropy-
lene, capron, or lavsan, or as bags made of polypropylene
sheet (Table 1). The load capacity of such soft containers
ranges from 500 to 2000 kg. No problems arise in packing
material in a flexible container.
A difficult problem in using flexible containers for dusty
and powder materials is that of emptying them. There are
various mechanical devices including for example a device
for unloading loose materials from soft containers with bot
tom outlet made by the firm of VSEMUTÔ, type RMK-T),
for handling soft bags.
Standard devices contain mobile elements, various forms
of grip, levers, and a considerable number of components,
which complicates the design and reduces the reliability.
The devices are quite large. Some operations in handling
flexible containers are performed by hand. When the bags
are discharged, much dust is formed, which is removed by a
suction system. The mechanisms are serviced and repaired
by highly qualified staff. To eliminate the above shortcom
ings, a supporting vessel has been developed for a flexible
container [1 – 3]. Figure 1 shows an industrial plant for
handling a flexible container with a design load of 1000 kg.
The supporting vessel works under pressure, and its wall
thickness is important. One calculates the thickness from the
maximum pressure P of the medium in the vessel, which
under emergency conditions may attain the pressure of the
compressed air in the supply. Most industrial compressed-air
networks have a working pressure of 0.6 MPa, while the
vessels are pressed at a pressure of 0.9 MPa. As there are
possible pressure surges, we take the calculated value
P = 1 MPa. The vessel material is steel 20 with a bending
strength of 140 MPa. The welded joints in the vessel are
two-sided butt joints, which are produced manually by elect-
ric welding. The welded-joint weakening factor is ö = 0.95
(Table 14.7 of ).
Refractories and Industrial Ceramics Vol. 48, No. 1, 2007
1083-4877/07/4801-0040 © 2007 Springer Science+Business Media, Inc.
State Management Board, Ural State Technical University —
Ural Polytechnical Institute, Russia.
TABLE 1. Polypropylene Bag Characteristics
, cm Sheet
66 (14 ´ 29)
80 80 35
92 (14 ´ 29)
85 125 30
82 (15 ´ 30)
80 102 20
84 (15 ´ 30)
80 113 20
87 (15 ´ 30)
80 113 20
with mount 50 100 80 131 50
56 95 88 111 20
50 100 70 72 —
55 105 70 83 —
78 120 65 125 —
87 130 65 147 —
95 150 80 230 —
The dimensions of the valve neck are given in parentheses.