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A Lasting Connection: Sewage and Water Pumps

With new homes comes the need for infrastructure—including sewage systems. One of Bulgin’s customers is a key player in the field of wastewater and sewage management.

Manufacturing sewage pumps and grinders, this customer specialises in designs that allow sewage systems to be installed in remote or awkward locations.

Instead of using traditional large-diameter pipes and relying on gravity to carry away wastewater, the client’s pump design pushes sewage through small diameter pipes in any landscape/terrain to beat the effects of gravity.

New Applications in Tough Conditions

The client required a new means to connect these pumps to their power supplies. These connectors would also have to provide additional protection on top of the all-important sealing that allows connectors to function in harsh environments.

The Buccaneer series of circular connectors is designed to provide excellent protection against water ingress. However, like most conventional connectors, the Buccaneer series is only sealed externally.

In some situations, moisture can work its way into the cable itself, particularly when cables are left submerged. The material used for the sheath can allow water or air to enter the cable, then pressure forces it to travel along the length of the cable.

Once the moisture reaches the connector fitted to the end of the cable, it can contaminate the connector itself. This has the potential to cause dangerous faults that risk both the functionality of the equipment and the safety of the users.

This was one of the client’s key concerns. To mitigate it, normal sealing tests would be carried out on a mated pair of connectors. The connector would be immersed in 10 meters of water for a period of two weeks.

After the test period, the connector would be inspected to ensure that the seals maintained their integrity and that no water had leaked into the connector.

Protecting from Water

Preventing water from migrating along the cable into the connector requires additional features.

To achieve this additional level of sealing, the rear of the connector is filled with epoxy. This is a common technique for connectors that are designed to be used with pressure bulkheads but is less commonly employed in cable connectors.

However, Bulgin was able to redesign the flex cable mounted 6000 series connector. This enables epoxy sealing of the cable connector as well as the bulkhead receptacle.

The testing required to ensure that water could not work its way through the cable into the connector needed a new procedure.

Once fitted to the connectors using the epoxy technique, air was to be injected through the sheath and insulator of the cable at a pressure of 0.344 bar (5 psi or 34.4 kPa). Sensitive equipment was to be used to listen for air leaking into the connector body. If such a leak was detected, the test was failed.

The size of the pump created another challenge for the client, as it prevented the use of a conventional circular connector with a jam nut.

Circular or cylindrical connectors are highly suitable for use in harsh conditions. Their physical shape makes them highly robust, and the circular interface makes sealing against water ingress relatively simple.

In contrast to conventional rectangular connectors, an increase in the number of terminals--or an increase in the size of the terminals themselves--will result in a connector of a larger diameter.

An Alternative Approach

Circular panel mounting connectors are often fixed using a jam nut. This is tightened from behind the fixing panel to create the secure installation required to provide mechanical strength and watertight sealing.

However, the use of a jam nut requires a significant amount of space behind the panel to allow installers to gain access with a spanner.

In the case of the sewage pump, this space was not available. Instead, the client requested that the panel-mount connector should provide its own method of fastening.

Instead of a conventional jam nut arrangement, Bulgin redesigned the housing of the connector to form its own threaded mounting.

In this way, the client could screw the connector directly to the enclosure surface, removing the need to access the rear of the connector and thus saving a considerable amount of space.

Working directly with the client’s design team, Bulgin was able to create a new concept for mounting the popular Buccaneer circular connector.

Based upon the 6000 series, a 3D-printed model was manufactured within 48 hours of the initial call, providing the client with a fully functional prototype for evaluation.

Once the mechanical design was proved, Bulgin commenced manufacture of the product. As the airtight seal was such an important feature for the client in the field, Bulgin investigated the best means of testing the completed connector.

The decision was made that, to ensure the long-term reliability of the connector, the same pressure testing equipment would be required to provide 100% inspection during production.

A New Solution

Although the Buccaneer series has long been used in similar harsh environments, the resulting Bulgin connector set a new standard for this demanding application.

Designed as a small, panel mounting solution with a previously unused contact arrangement, the connector provides a sealed and airtight solution for the very particular demands of the customer.

Bulgin has nearly a century of experience in developing connectivity products for some of the most demanding conditions. Bulgin is ideally equipped to work with customers in a diverse range of industries and provide solutions for a vast array of applications.

Contact us to learn more.

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