OLI PG · air cannons

Air cannons for silos and hoppers

A pressure vessel emptied through one fast valve that lays an air blade down along the wall — at 3 to 6 bar.

Wood chips, paper, textile fibres, plastic shavings, bran. Materials with a large and irregular particle shape hold together differently from a fine powder: they interlock, span a bridge across the outlet and stay behind on the cone wall when the rest has run out. Vibration and aeration work on the mass from within and fall short. An air cannon does something else. The PG is a pressure vessel charged to 3 to 6 bar and emptied through one fast valve: between 2.6 and 21 litres of free air leave the nozzle in an instant. The jet is aimed parallel to the internal wall, and the effect is an air blade that sweeps the hopper surface clean. It does not run continuously but in shots — at an interval you set yourself, from 30 seconds to 45 minutes.

PG3–6 bar2.6–21 l per shot−20 to 80 °C6–21 kg

Tell us about your plant See the specifications

Download the datasheet Dimensions, specifications and all variants PDF · 4 pages · 107 kB

A PG air cannon seen from the front at an angle: a ribbed aluminium pressure vessel on a black mounting plate, with a coil and manual override on top and a black nozzle pipe out through the plate.

The problem

Three ways the material stays behind

An air cannon solves three things: the bridge over the outlet, the rathole through the middle and the emptying that never finishes. Any plant engineer knows the first two. The third is the one that costs most, because it does not stop production — it just eats the capacity.

Bridge over the outlet

Chips, flakes and fibres interlock and span an arch across the opening. The silo is full, the discharge works in empty space, and nothing comes out.

Rathole through the middle

A narrow shaft runs down through the centre while the rest stands still along the wall. The silo looks like it is emptying, but most of the contents stay put — and get older by the day.

Incomplete clean out

The material does come out, but a cake stays behind on the cone wall and the silo never empties completely. This is what the air blade is built for: the jet runs along the wall and takes the cake with it.

Walkthrough

Four steps through the product

Click through: from the silo that never empties to the choice between the three sizes.

01 The problem

Drag the line from side to side

Without cannons the material carries its own weight: the bridge stands across the outlet and a cake stays behind along the cone wall that never comes out. With cannons an air blade runs down along the wall and tears the cake loose. It is the same silo on both sides of the line.

02 The technology

The cannon sits on the outside of the wall, and only the nozzle goes in. The nozzle is an elbow: it turns the jet so the shot lies down like a blade along the inner face instead of drilling into the mass. The valve sits in the head and empties the vessel in an instant.

03 The installation

The circuit is short: a filter and a flow control valve. The difference from an aerator is that the cannon needs a signal to fire. The timer sets the interval from 30 seconds to 45 minutes, and one electronic board can take up to fifteen cannons and fire them in turn.

The compressed air The PG runs on compressed air at 3 to 6 bar. The pressure decides how hard the shot is: the same cannon gives almost twice as much air at 6 bar as at 3.
The filter The air has to be clean. The air quality has to be class 5.4.1. A fast valve that opens and closes many times a day is the wrong place to have dirt in the air.
The control The timer is set from 30 seconds to 45 minutes, and one electronic board can control up to fifteen cannons. The coils are available from 24 volt AC and DC up to 230 volt.
The cannons on the cone The vessels sit outside, and only the nozzles pass in through the wall. Each nozzle lays its blade down along the inner face. The shot is powerful: the maximum noise level is 105 dB(A), and that belongs in the choice of position.
The outlet What comes out is what it is all about. The cake along the wall has been torn loose, the bridge is broken, and the cone empties all the way round instead of through a hole in the middle.

04 The choice

Which sizePG 40PG 63PG 80

The three are drawn to the same scale. Which one fits depends on the size of the cone, what you handle and what the compressed air can deliver — we are happy to work it through on your own silo.

The three are the same cannon in three volumes. Click between them — all three are drawn to the same scale, so the difference is there to be seen and not just read.

The technology

One shot, along the wall

An air cannon is a pressure vessel. The vessel stands full of compressed air at 3 to 6 bar and does nothing — until the valve opens. The valve is integrated in the head, it is fast, and it empties the whole vessel in an instant: 2.6 litres on the smallest at 3 bar, 21 litres on the largest at 6. Afterwards the vessel recharges, and nothing more happens until the next shot. The duty cycle is therefore discontinuous, and that is why the consumption can be so low: the cannon only uses air in the seconds it is working.

The direction is the whole point. The jet is aimed parallel to the internal wall of the silo, so that materials with an irregular shape, dry and light, flow down without any accumulation. The nozzle is an elbow: it takes the air in through the wall and turns it, so the shot lies down like a blade across the surface instead of drilling into the mass. That is the air blade, and it is what sweeps the hopper surface clean.

It is not quiet, though. The maximum noise level is 105 dB(A), and that is a figure that belongs in the planning of where the cannons sit and who works nearby. The air also has to be clean: quality class 5.4.1, with a filter and a flow control valve in the circuit.

Data

Technical specifications

Application	Hopper and silo
Material in the silo	Large size, irregular shape, fibrous dust and flakes
Problem solving	Bridge, rat-holing and incomplete clean out
Duty cycle	Discontinuous
Working pressure	From 3 bar to 6 bar (from 43 psi to 87 psi)
Air per shot	2.6 to 21 litres, depending on size and pressure
Pneumatic circuit	Filter and flow control valve
Air supply quality	Class 5.4.1
Working temperature	−20 to 80 °C (−4 to 176 °F)
Max noise level	105 dB(A)
Technology	High pressure jet
Material	Aluminium body, steel plate and aluminium head
Air inlet	1/8 in BSPP on the PG 40, 1/4 in BSPP on the PG 63 and PG 80
Directives	2014/34/EU category 3D and 2006/42/EC, designed to EN 1127-1 and EN 12100
Position	Internal application, in contact with the material. The vessel sits outside on the wall, the nozzle passes in through it

The dimensions

Three sizes, the same build

What separates the three is the volume of the vessel — and therefore how much air there is in one shot. A is the side of the mounting plate, B its thickness, D the overall height of the cannon, Ø E the diameter of the nozzle pipe and F how far the nozzle projects from the plate.

Air per shot in litres, dimensions in millimetres
Model	3 bar	6 bar	A	B	D	Ø E	F	Weight
PG 40	2.6 l	4.6 l	130 mm	20 mm	223 mm	27 mm	61 mm	6 kg
PG 63	6.4 l	11.6 l	160 mm	20 mm	263 mm	42 mm	88 mm	14 kg
PG 80	12.5 l	21 l	200 mm	25 mm	318 mm	48 mm	104 mm	21 kg

The number in the model name follows the size of the vessel: the PG 40 is the smallest and the PG 80 the largest. The air inlet is 1/8 in BSPP on the PG 40 and 1/4 in BSPP on the other two, and the pipe diameter is 8 millimetres on all three.

Components

The vessel, the valve and what fires the shot

A PG comes with a mounting plate. The plate bolts to the silo wall, the nozzle pipe passes in through it, and the vessel stays outside. The valve is integrated in the head, and firing can be electric or fully pneumatic.

A PG air cannon seen straight from the front: the ribbed vessel on the black mounting plate, with the nozzle pipe pointing down below the plate.

The vessel and the plate PG 40 · 63 · 80

The pressure vessel itself is aluminium and stands on a square steel plate that is included. The plate has slotted holes in all four corners so it can be aligned, and the nozzle pipe passes in through the middle.

Sizes	PG 40, PG 63 and PG 80
Plate side	130, 160 or 200 mm
Overall height	223, 263 or 318 mm
Weight	6, 14 or 21 kg
Material	Body and head in aluminium, plate in steel

The plate bolts on from the outside of the silo wall.
The nozzle pipe passes in through the wall and turns, so the jet runs along the inner face.
The vessel sits outside and can be reached for service.
The mounting plate is included in the delivery.

A PG air cannon seen from behind at an angle: the coil and the manual override on top of the head, and the air connection on the side of the vessel.

The valve and the firing

The valve sits inside the head, not as a loose component in the pipe, and it is what makes the shot fast enough to become a blade rather than a puff. On top sits the coil with a manual override. Where the plant has to run without electricity at the cannon, a fully pneumatic activation kit is available instead.

Valve	Integrated in the head
Coils	24 V AC and DC up to 230 V
Timer	Adjustable from 30 seconds to 45 minutes
Control	Electronic board for up to 15 cannons
Without power	Fully pneumatic activation kit

The coil opens the valve and the vessel empties in an instant.
The timer decides how often it fires.
One electronic board can control up to 15 cannons and fire them in turn.
The manual override sits on top of the head.

How many cannons are needed and where they should sit depends on the dimensions and angle of the cone, what you handle, and what the compressed air can deliver. Tell us, and we come back with a size, a number and a layout.

Application

Where it sits and what it works in

Plant	Silos and hoppers
Materials	Powders of large particle size and irregular shape, fibrous powders and flakes. Typically wood fibres, textile fibres, paper, plastics and bran
Benefits	Compact design with integrated solenoid valve, suitable for bridge breaking, economical, easy to install, low air consumption and mounting plate included
Sectors	Building and construction, food and feed, heavy industries, plants and machinery, plastics and chemical processing, recycling and environment technology, and renewable energies
Ex areas	Conforms to directive 2014/34/EU in category 3D, that is dust zone 22

FlexCore

Getting the air to every cannon

A cannon is nothing without compressed air at the connection. The hoses come from our own range.

Yellow EPDM compressed air hose, coiled.

ARIACORD/YELLOWRugged EPDM hose for compressed air and water, 25 bar. Weather and UV resistant, so it can live outdoors beside the silo.

ARIAFORM/15TPE air hose for industry and workshop. Handles water, air and oil-laden compressed air, and is light enough to move around.

ARIAFORM/TPULight polyurethane hose for tools and reel systems. The softest of the three, where the hose has to follow the work.

See the full hose range →

Further

Which size, and how many?

Tell us the dimensions and angle of the cone, what you handle, and what the compressed air can deliver. We come back with a size, a number and a price — not with a catalogue.

Contact us Try the product selector