Filling of drums with toxic products in a Belgian chemical factory
It was a real challenge for Feige to design a fully automatic filling machine to fill steel bunghole drums. It was of first priority that humans and environment were supposed to be a hundred percent safe.
Taking our well-proven automatic drum filler as basis we have finally realised a technical highly-efficient machinery without any negative affect on the total rentability.
The drums are centred and positioned, automatically debunged, vacuum-checked on air-tightness, filled according to Weight & Measures, safely bunged and moved off – all this in strict conformity with ATEX-regulations, for sure.
A Belgian chemical factory looked for a fully-automatic filling machine to fill its liquid products – said to be very “difficult” in handling – into steel bunghole drums 216,5 ltrs. (EN210). The product was combustible, in higher concentration even toxic, respiratory paralysing, skin-irritating liquid, spreading a very ahkward odour already at small quanti-ties.
Here, it was our utmost aim to provide for a technical highly-efficient machine to protect humans and environment likewise. All this at high output efficiency and positive total return on investment.
We decided to take our well-proven Feige automatic drum filler as basis, which takes automatically over the bunghole drums from an incoming roller conveyor. The drums are centred, positioned, debunged and then filled by means of the automatic Feige-scale. Then the drum is closed safely and reliably with a bunging plug and transferred onto the outgoing roller conveyor. Because of the product’s flammability the automatic drum filler had to be designed according to ATEX-regulations for hazardous areas.
Extensive protection and safety devices
By means of a vacuum leakage test the tightness of the plug is checked on the empty drum.
This shall make sure that there aren’t any impurities inside the drum and that the plug sealing is closing reliably. Only impeccable drums are debunged and advanced accord-ingly.
As next step the inside of the drum is purged with nitrogen. The inerted atmosphere is supposed to protect the product to be filled and prevent ignitions of the fill gases. Then the drum enteres the protective cabin of the filling area. This is separated by automatically-operated lifting gates at the entrance and exit side. The product hose passage is covered with brushes and at operator’s side there are well-tightening maintenance sliding doors. The top roof cover comprises the connection for the cabin exhaust. Prior to filling, the drum is earthed at its bottom via earthing cutters. Earthing is electrically monitored. Filling only starts when the container is correctly earthed. In case earth contact is interrupted, the filling valve will immediately shut off.
Filling is done in below-surface filling mode because of the product’s dangerous features. After a tare check the long filling lance of the filling valve lowers almost down to the bot-tom of the drum. The valve opens and the immersed filling lance moves up with raising product level. This shall prevent that the product gets swirled and foaming. Electrostatic charges are diverted via the immersed filling lance. To prevent that the filling lance never gets un-immersed, the upward movement is level-controlled via a pipelet pressurized with inert gas.
In case the product level should raise inadmissibly in the upper fill position, the fill process is immediately stopped (overflow sensor).
A second safety is achieved by the opto-electronic limit indicator (approved as per VbF §12 and WHG §19).
No filling gases in the protective cabin
Filling gases escaping from the bunghole during filling are absorbed by a jacket pipe placed around the filling lance and discharged by customer’s exhaust. The jacket pipe must not touch the drum’s top, not to influence the weigh-scale. But there shall also be a narrow gap when there are tolerances in drum heights. In this gap then develops an air velocity that is high enough to prevent the filling gases from discharging into the protective cabin even if secondary air supply is low.
The narrow gap is achieved by a specially-controlled actuator of the jacket pipe (patent). When the filling lance dives out of the filling product after the fill process has been fin-ished, drips running down the lance’s tip are sucked into the valve rod and then fed via a separator into a residula container provided on site.
Moreover, the filling lance is surrounded by a bellow-type sealing. There won’t come any odours of the product film out of the bellow at the lance’s tip, as it is permanently sucked off.
Just after filling the closing process is done, without moving the drum. The tool carriage moves the bunging tool into its working position and the bung is reliably screwed into the bunghole with a defined torque and monitoring of bunging depth.
Now, the “dangerous” situation is over.
The lifting gate at the exit side of the protective cabin opens and the clean, filled, reliably closed drum is transferred onto the outgoing roller conveyor. More than 50 drums per hour can this Belgian chemical factory fill with a Feige automatic drum filler and this with a pure conscience to protect humans and environment the same way.
