Bulk storage hoppers, bins and silos for powders and bulk solids · designing from measured flow properties, mass flow versus funnel flow, hopper angle, wall surface and outlet size to prevent arching and ratholing, feeders, and structural loads from solids, wind, seismic and gas pressure
A bulk storage hopper, bin or silo stores a powder or granular material and releases it through an outlet in its converging base. Whether material flows reliably depends on the material's measured flow properties as much as on the vessel. Ask three things first: what material and conditions (moisture, temperature, storage time) the hopper must handle, what capacity and discharge rate you need, and whether flow problems such as arching, ratholing or segregation must be designed out.
Storage hoppers, bins and silos for powders and bulk solids, with their hopper sections, outlets and discharge feeders. Liquid storage tanks, mixing hoppers for drilling fluid and powder-coating feed hoppers have their own pages except where compared.
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ASTM D6128 covers apparatus and procedures for measuring the cohesive strength of bulk solids in continuous flow and after storage at rest, along with internal friction, bulk density and wall friction on various wall surfaces. ASTM states that this information is used in designing storage bins and hoppers to prevent flow stoppages from arching and ratholing, including choosing the slope and smoothness of hopper walls to give mass flow. Data for structural design can also be derived. [1]
The standard's significance section lists the problems that design must address: flow stoppages from arching and ratholing, flooding of powders, segregation of particle mixtures, usable capacity well below design capacity, caking and spoilage in stagnant zones, and structural failures. It says designing bins and hoppers from measured flow properties means “most flow problems can be prevented or eliminated”. For solids with a significant percentage of particles finer than about 6 mm (ASTM gives one third or more as the guide), the fines govern cohesive strength. [1]
Jenike & Johanson, a bulk solids engineering firm, lists the design inputs for silos, bins and hoppers: a general configuration that meets capacity and space limits, material flow properties used to select design parameters, the hopper shape, angle and internal surface needed for the chosen flow pattern, an outlet size and shape engineered to avoid poor flow and ensure the discharge rate, and feeder selection to maintain reliable discharge. [2]
Give the supplier the material and its particle size, moisture, temperature and bulk density, flow property test results if available, the storage time at rest, the capacity and discharge rate, the required flow pattern (mass or funnel flow), the outlet and feeder arrangement, the wall material and finish, the site loads (wind, seismic), dust and explosion protection, and the codes that apply.
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Jenike & Johanson lists the load cases to consider for silos: solids-induced loads in mass flow, funnel flow and eccentric discharge; external loads from wind, seismic action and ancillary equipment; and internal loads from gas pressure. It notes that silo design codes tabulate values for only a few materials, and that the codes recommend testing the actual bulk material when possible. [3]
Its project examples include a converging/diverging mass-flow silo for cohesive wet bran, an expanded-flow silo retrofit for hot lime at 427 °C (800 °F), and an air-assisted discharge silo for feeding kaolin clay into railcars. [2]
Where the hopper or silo stores grain or grain products, US rule 29 CFR 1910.272(g) applies to employee entry into bins, silos and tanks. A permit is required unless the employer's representative is present throughout. All mechanical, electrical, hydraulic and pneumatic equipment that endangers people inside must be de-energised and locked out or otherwise prevented from operating. The atmosphere must be tested for oxygen (unsafe below 19.5%) and, where suspected, for combustible gases and toxic agents. Walking down grain to make it flow is prohibited, and an employee above stored grain or on grain deep enough to engulf them must wear a harness and lifeline that stop them sinking further than waist-deep. [4]
Design features that reduce the need for entry, such as an outlet and feeder sized for reliable flow, and access points that allow equipment to be locked out, belong in the specification from the start. [2] [4]
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This is a functional reference built from the sources cited; it is not one maker's design.
| Component | Role | Fix in the order |
|---|---|---|
| Hopper body and walls | Converging section whose slope and wall smoothness set mass or funnel flow. [1] [2] | Hopper angle, wall material and finish. |
| Discharge outlet | Sized and shaped to avoid poor flow and meet the discharge rate. [2] | Outlet dimensions and gate or valve. |
| Feeder | Selected to keep discharge reliable. [2] | Feeder type, rate and drive. |
| Support structure | Carries solids, wind, seismic, equipment and gas-pressure loads. [3] | Structural design basis and code. |
| Access and isolation | Entry permits, lockout and atmosphere testing for grain bins (US). [4] | Access doors, lockout points, ventilation. |
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A hopper or silo quotation needs values for your material. The table explains each field, gives published information where a reviewed source states it, and says what to ask the supplier for.
| Field | What it means and published information | Ask the supplier for |
|---|---|---|
| Flow properties | Cohesive strength, internal and wall friction, bulk density (ASTM D6128). [1] | Test data on your material. |
| Flow pattern | Mass flow or funnel flow. [3] [1] | Pattern and hopper angle. |
| Outlet | Size and shape to avoid poor flow and meet discharge rate. [2] | Outlet dimensions. |
| Feeder | Selected to keep discharge reliable. [2] | Feeder type and rate. |
| Loads | Solids, wind, seismic, equipment, gas pressure. [3] | Structural design basis. |
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Paste it into your enquiry below or into an email to a maker, then replace every bracket.
Material: [type; size; moisture; temperature; bulk density] Flow tests: [results or request] Storage: [capacity; time at rest] Discharge: [rate; feeder; outlet] Design: [mass/funnel flow; wall finish] Site: [wind; seismic; dust/explosion protection] Codes: [structural and safety codes]
These companies list this product on their own websites.
Its website lists cement, fly ash, mineral powder and dry mortar silos.
Product scope checked 2026-10-12
Its website lists cone-bottom silos.
Product scope checked 2026-10-12
Explore company information and manufacturing capabilities, then discuss the scope of your project with a relevant supplier.
ASTM D6128 names arching and ratholing as causes of flow stoppage, which design based on measured flow properties is meant to prevent. [1]
Cohesive strength, internal friction, bulk density and wall friction, using shear testing to ASTM D6128. [1]
Jenike & Johanson lists solids loads in mass flow, funnel flow and eccentric discharge, plus wind, seismic, equipment and gas pressure loads. [3]
29 CFR 1910.272(g) requires a permit, lockout of hazardous equipment, atmosphere testing (oxygen below 19.5% is unsafe), and a harness and lifeline when there is an engulfment hazard. [4]
Sources checked 2026-10-12. The ASTM page is the public scope and significance summary of D6128; the full standard is sold by ASTM. Jenike & Johanson describes its own engineering approach. The eCFR section is the current US grain handling rule.
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