Drum Bungs And Bungholes: Explanations And Tips - Fidel Fillaud

For packaging your foodstuffs, petroleum products, chemicals, flavourings, cosmetics, pharmaceuticals, and other liquids, you use drums fitted with bungs. What is a drum bung? How do you stop and unstop a drum’s bunghole? Find some explanations and tips below!

Definitions

Bunghole : one of the round openings on the top of an upright drum, used for filling and emptying

• On a PE drum, the bunghole is formed directly during moulding
• On a steel drum, the bunghole is added later as a press-fit octagonal flange in the drum top or lid

Bung: the plug that fits into the bunghole to close the drum after filling

Different kinds of bung

Drums of this kind have one or two female threaded bungholes closed off with male threaded bungs. Bungs come in a variety of types; here are a few examples:

Bung for plastic and combo drums

MATERIAL	FORMAT	THREAD	FEATURES	SUITABLE CAPSEAL
PP	4N	S56x4 BCS	> solid > solid + EPDM vent in (regassing) valve > solid + EPDM vent out (degassing) valve > solid + microporous membrane with protection bulb (pressure exchanger	2” Tab-Seal metal capseal (optionally drilled) 2” or 2.5” Push-Lock plastic capseal
	4N	S70x6 BCS	> solid > solid + 3/4 threaded > solid + EPDM vent out (degassing) valve > solid + microporous membrane with protection bulb (pressure exchanger
	6N	S56x4 BCS	> solid > solid + 3/4 threaded > solid + 3/4 threaded, microporous membrane with protection bulb (pressure exchanger)	3/4” & 2” Tab-Seal metal capseal (optionally drilled)
	2N	S24x46 BCS	> solid

N indicates Nocks (lugs) So a 4N bung has 4 lugs

Bung for steel drums

MATERIAL	FORMAT	THREAD	FEATURES	SUITABLE CAPSEAL
galvanized steel with or without lacquer coating	none	G2'' BSP (gas pitch)	> solid + EPDM vent in valve (regassing) > solid + EPDM vent out valve (degassing)	Tab-Seal metal capseal (optionally drilled) SambaCap plastic capseal
	none	G3/4'' BSP (gas pitch)	> solid
PP	4N	G2'' BSP (gas pitch)	> solid > solid + 3/4 threaded > solid + EPDM vent in valve (regassing) > solid + EPDM vent out valve (degassing) > solid + microporous membrane with protection bulb (pressure exchanger)
	2N	G3/4'' BSP (gas pitch)	> solid > solid + microporous membrane with protection bulb (pressure exchanger)
PA	4N	G2'' BSP (gas pitch)	> solid > solid + 3/4 threaded > solid + EPDM vent in valve (regassing) > solid + EPDM vent out valve (degassing)
	2N	G3/4'' BSP (gas pitch)	> solid

Illustrated examples of some types...

2” solid 2” bung - coarse thread S56x4 - Ø50mm	2" DIN solid 2” bung - thread S70x6 - Ø69.8mm
2” solid + degassing valve	2” + ¾” 2” bung - coarse thread S56X4 + 3/4'' BSP hole (gas pitch)
2” solid - galvanized steel fine thread, BSP (British Standard Pipe/ Gas pitch)	3/4” solid - galvanized steel BSP fine thread

Temper evident capseals

To “seal” the bung, a tamper evident capseal is required. Both metal and plastic capseals can be had. Some examples are shown below:

Metal crimp-on capseals (¾” and 2”), compatible with steel and plastic drums

For use on a degassing bung, there are special degassing capseals featuring a very small hole

Manual clip-on PE capseal

For steel drums (¾' et 2')	For PE drums (2' et 2' DIN)	Push-lock capseal (fits over a compatible push-lock bung)

Manual application and removal of drum bungs

Various kinds of tool can be used to close and/or open drums manually, some of which are shown below:

Hammerhead multifonctions wrench

Pocket-size model for opening 2” and ¾” bungs

Crimping pliers for metal tamper-evident capseals

• Manual crimping pliers for 2” metal capseal
• Manual crimping pliers for 3/4” metal capseal

A few explanations and tips

When can a “Flexspout” bung be used?

The “Flexspout” bung has a retractable pour spout for easier drum emptying (a little like the spout of an engine oil can).

This bung can be used only on drums with a specific bunghole.

The bung is crimped onto on the drum, an operation that requires specific manual or pneumatic crimping pliers.

=> How can a capseal be made more reliably tamper evident?

Unbranded capseals are sold all over the world and it is easy to swap one for another.

Customization is therefore an excellent means of guaranteeing evidence of any tampering.

Which bunghole takes a 3/4” BSP tap?

On a steel drum, the tap goes in the drum’s 3/4” bunghole. Venting then takes place through the 2” bunghole. On a PE* drum, the drum’s 3/4” bunghole is the vent. Therefore the tap goes in the drum’s 2” bunghole via the 3/4” hole of a 2” + 3/4” bung.

(if the drum comes with a plain 2” bung, it must be replaced by a 2” + 3/4” bung to accept the tap)

*Fidel Fillaud supplies PE drums fitted with a 2” +3/4” bung as standard.

Bungs and accreditation

Generally speaking, a UN rating is valid only for a specific body/accessory pairing. Therefore the body must always be fitted with the same accessory as specified in the relevant rating certificate.

If a drum is delivered with one type of bung and the user wants to use a different bung, the new pairing must be checked for accreditation.

example of adapter 2” - S56x4 male / 2” BSP female

=> When is an adaptor needed?

Accessories—2” tap, pump, or other—are initially intended for a BSP fine thread (gas pitch), which is standard on the 2” bunghole of steel drums.

On PE drums on the other hand, the screw threads are different, so an adapter is needed.

Recommendations when closing a drum

Take extra care to screw the bung in properly to avoid leaks, but avoid over-tightening => always comply with the recommended tightening torque.

Over-tightening a bung on a plastic drum can damage the bunghole (distending or even splitting it), which not only can hinder fitting of the tamper evident capseal but also can give rise to leaks.

On a steel drum, over-tightening can crush the bung’s seal, causing it to lose some of its sealing efficiency.

Pay attention to the seal

For guaranteed leak tightness, a bung must be fitted with the correct seal (rubber, PE, S.EPDM, etc.). The correct choice depends on the nature of the drum contents.

The information in this article refers only to the types of packaging distributed by Fidel Fillaud

Any reproduction of this article is prohibited without the written consent of Fidel Fillaud or attribution