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AIR KNOCKER (Impactor)
Pdf brochure DOWNLOAD (Air knocker/Opecon, 1-page 445kb)

Pdf brochure DOWNLOAD (Air Knocker - Example for use, 2-page 147kb)

Pdf brochure DOWNLOAD (Air Knocker -
Installation, 2-page 201kb)

Pdf brochure DOWNLOAD (
Relay knocker, Stainless knocker, Control, 2-page 255kb)

Questionnaire DOWNLOAD (Survey - Flow Aid System, 103kb)

Questionnaire DOWNLOAD (Survey - Flow Aid System, 33kb)

Air Knocker

Direct Type

A piston strikes a wall by the force of a compressed air. It is the instrument which prevents adhesion and a blockade of a bulk material by the impact force Moreover, it can be used only by air feeding and excels in safety and economical efficiency. It is effective in a bulk material with the characteristic which will adhere when a vibration is given.

The stroke of the piston which moves, and the knocker itself are not moved, it can hit. A usage also spreads on idea. Moreover, it can use also like a indirect impact type.

Indirect Type

A piston strikes a knocker`s body a base by the force of a compressed air. It is the instrument which prevents adhesion and a blockade of a bulk material by the impact force Moreover, it can be used only by air supply and excels in safety and economical efficiency. It is effective in a bulk material with the characteristic which will adhere to if a vibration is given.
  <Comparison between air knocker and piston vibrator>

Multiple Air Knocker principle and features

Compressed air is introduced to the air tank of the Knocker and
the piston momentarily works by opening/closing the inside valve
using three-way valve. The generated impact will avoid the powder
sticking/clogging problem at hoppers. This system eliminates the
manual hammering work. Fully automatic operation is possible.
Hammering strength is adjustable by changing pressure.
Multiple knockers can be installed by single valve action.
Relay knocker
Tubing for Multiple Air Knocker installation
When multiple installation, compressed air is supplied through three-way valve to tank-center port of the knocker. And from the next sub port, another tube is connected to the next air knocker main port. And the 3rd and more knocker can be connected in the same way. All the air knockers work almost at the same time (very short time lag). Multiple air knocker can be operated by single valve action, which decreases the initial cost. Maximum quantity (3 to 10 units) depends on the control and the three-way valve. (Patented)
Air knocker installation example
Examples of use on pipe 
Pipe size Pipe thickness (mm) Recommended air knocker
3" 4.2 RKV30PA
4" 4.5 RKV40PA
5" 4.5 RKV40PA
6" 5 RKV40PA-RKV60PA
8" 5.8 RKV60PA
10" 6.6 RKV60PA
12" 6.9 RKV60PA
* The above is recommended for standard use.
* The model may change depending on the flowing material inside. 

Bridging occurs when materials cling to the wall or compact above the discharge opening of the lower part in the hopper, and the flow of materials in the upper part is interrupted.
Arching occurs when materials in the lower part of the hopper flow out from the discharge opening, and an arch strong enough to support the entire head load in the hopper is formed
Rat holing occurs when materials flow only above the exit, and form a tube that leaves the hopper filled with "dead" materials, which will not move. 
Clinging materials and also materials easily influenced by the moisture and the temperature adhere to the wall and refuse to flow 
Indirect EXEN Air Knocker Models (carbon steel & stainless steel)
ferrule type  ferrule type
RKVS15   RKVS15-F  RKVS20  RKVS20-F RKVS30  RKVS40 & 60 
* RKVS30-F (ferrule type) is now available.

SPECIFICATIONS of indirect air knocker (carbon steel)
Model Working Pressure
Percussion Cycle
Air Consumption
Percussion Energy
Impulsive Force Total Weight
(kg-m/s) Suitable hammer (Ibs)
RKV20P 0.3-0.7 1-60 0.04-0.10 .4.3-8.3 0.6 below 1.0 0.7
RKV30PA  0.05-0.13 5.49-13.1  1.70-2.60  below 1.0  1.3 
RKV40PA 0.15-0.37 9.22-22.3 2.86-4.42 1.0-1.5 3.4
RKV60PA 0.33-0.77 20.60-49.0 6.80-10.50 1.5-3.0 8.8
RKV80PA 0.60-1.40 45.10-109.0 15.00-23.30 3.0-8.0 13.7
RKV100PA 0.98-2.28 82.40-201.0 28.70-44.50 6.0-15.0 30.8
 How to determine the recommended model/quantity from
hopper size & hopper plate thickness


Model A C D G H I J K L M N
RKV20P 57 57 6 1/8 70 (25) 6.5 44 6 28 21.7
RKV30PA 66  70  8  95  8.5  55  8  35  27.2 
RKV40PA 86 95 12 140 12.5 70 13 60 34.0
RKV60PA 115 138 14 183 14.5 110 15 80 76.3
RKV80PA 146 148 16 1/4 222 (28) 17.0 120 18 90
RKV100PA 175 208 20 270 21.0 170 23 115 114.3


(1) When wall thickness in the installation part is thin, prepare the reinforcing plate of 3 2 to 6 mm thick, and weld the center and around the whole reinforcing plate in front fillet welding to the hopper for transmitting percussion force more efficiently.


Model Square Plate Round Plate
RKV30PA 150*150 mm, t3.2 150 mm dia. t3.2
RKV40PA 200*200 mm, t3.2 200 mm dia. t3.2
RKV60PA 300*300 mm, t4.5 300 mm dia. t4.5
RKV80PA 400*400 mm, t4.5 400 mm dia. t4.5
RKV100PA 500*500 mm, t6.0 500 mm dia. t6.0

(2) Weld around the whole circumference of the base.
(3) For the model larger than RKV60, weld accessory reinforcing rib usually necessary for RKV30P and 40P.
(4) Tighten the body thoroughly, using accessory bolt, spring washer, and hard lock nut.
(5) Secure the knocker by suspending with wire rope to prevent the knocker from dropping.


When operating, considerable impact is given to welds. When welding, pad as much as possible to eliminate damage, which may be caused.
(air operated)
(air operated)
for relay knockers

for relay knockers

< Questionnaire for Exen air knocker >

Marketed by AAAmachine, Inc.(USA)
Tel: 1-800-996-0070

Manufactured by Exen Corporation
1-7-13, Hamamatsucho, Minato-ku, Tokyo 105-0013 Japan
Tel: +81-3-3434-8455, Fax: +81-3-3434-1658, E-mail

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300 Park Boulevard Itasca, IL 60143 USA E-mail

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