Proper installation of Hawke cable glands is essential for maintaining the integrity, safety, and performance of electrical systems, particularly in hazardous environments such as industrial, oil and gas, and petrochemical sectors. Hawke cable glands are engineered to meet rigorous standards and offer robust solutions for a variety of applications, including armoured and unarmoured cables. This article provides a detailed, step-by-step guide to installing Hawke cable glands, based on official documentation and technical specifications provided by the manufacturer and certified suppliers.
Understanding Hawke Cable Gland Components
The Hawke 711 cable gland is a common example used in industrial applications. It consists of eight main parts:
- Entry Boot: The initial point of contact between the cable and the gland, designed to protect the cable from mechanical damage.
- Compound Pot: A component used to apply sealing compound to the gland to ensure a secure and watertight seal.
- Diablo Grounding Device: A specialized clamping mechanism used to ensure electrical continuity and grounding in armoured cables.
- Two Nuts: Used to secure the gland components and provide strain relief.
- Backnut: The final securing component that fastens the gland to the enclosure.
- Optional Shroud: A protective cover that can be added for additional mechanical protection or to meet aesthetic requirements.
These components must be assembled in the correct sequence to ensure proper sealing, grounding, and mechanical integrity of the installation. The installation process involves preparing the cable, fitting the diablo grounding device, installing the compound pot, potting the gland with compound, and securing the gland to the enclosure using the backnut.
Selecting the Correct Cable Gland
Selecting the correct Hawke cable gland is the first and most critical step in the installation process. The gland must be compatible with the type, size, and configuration of the cable being used. The following factors must be considered:
- Cable Diameter: The gland must accommodate the outer diameter of the cable. If the cable is too large or too small for the gland, it will compromise the seal and mechanical strength of the installation.
- Armour Type: For armoured cables, the gland must be designed to handle the specific type of armour—such as steel wire armour (SWA), braid, or tape. The gland must include the appropriate clamping rings and sealing elements to secure the armour and prevent damage.
- Zone Rating: In hazardous environments, the gland must meet the required zone rating (e.g., Zone 1, Zone 2, Zone 21, Zone 22). This determines the level of protection against explosions and ingress of flammable substances.
- Ingress Protection (IP) Rating: The gland must provide the required level of protection against dust and water ingress. For example, an IP66 rating is often required for outdoor or high-moisture environments.
The manufacturer provides detailed specifications for each gland model, including the maximum and minimum cable diameters, recommended torque settings, and compatible cable types. These specifications are typically available in technical guides and product datasheets, which should be consulted before installation.
Preparing the Cable
Before installing the gland, the cable must be prepared according to the manufacturer’s instructions. The preparation process includes the following steps:
- Stripping the Cable Sheath: The outer sheath of the cable must be stripped to the correct length, ensuring that the internal conductors and armour (if present) are not damaged. The length of the stripped section depends on the gland model and the type of cable being used.
- Trimming and Shaping the Armour: For armoured cables, the armour must be trimmed and shaped to fit cleanly inside the gland. This prevents damage to the internal conductors and ensures that the clamping rings can grip the armour securely.
- Cleaning the Cable: The cable must be cleaned to remove any dirt, grease, or debris that could interfere with the sealing or grounding process. This is particularly important for armoured cables, where the grounding device must make direct contact with the armour.
Proper cable preparation is essential for ensuring a secure and long-lasting installation. Failure to prepare the cable correctly can lead to premature failure, reduced performance, or even safety hazards in hazardous environments.
Assembling the Hawke Cable Gland
Once the cable is prepared, the gland can be assembled according to the manufacturer’s instructions. The assembly process typically includes the following components:
- Entry Item: The first component to be installed, the entry item ensures that the cable is properly aligned with the gland body.
- Inner and Outer Seals: These seals provide the primary protection against dust and water ingress. The inner seal fits over the cable, while the outer seal provides additional protection against environmental exposure.
- Armour Cone and Clamping Ring (for armoured cables): These components are used to secure the armoured cable within the gland. The clamping ring applies pressure to the armour, ensuring that it is firmly held in place.
- Compression Nut: The final component in the assembly, the compression nut is used to secure the gland to the enclosure and apply the necessary pressure to the sealing elements.
The assembly must be performed in the correct sequence to ensure that all components are properly engaged and that the gland functions as intended. In particular, IP sealing washers must be applied where required to maintain the desired level of ingress protection.
Securing and Tightening the Gland
After the gland is assembled, it must be secured to the enclosure using the appropriate fastening method. This typically involves the following steps:
- Mounting the Gland: The gland is mounted to the enclosure using a hole that has been prepared according to the manufacturer’s specifications. The recommended clearance for the hole is typically +0.2mm on the nominal thread diameter, with a maximum clearance of +0.7mm. This ensures that the gland can be installed without damaging the enclosure or compromising the seal.
- Tightening the Compression Nut: The compression nut is tightened using two spanners—one to hold the gland body and the other to tighten the nut. The recommended torque setting should be used to ensure that the gland is secured without over-tightening, which could damage the sealing elements or the cable.
- Checking the Installation: Once the gland is tightened, the installation should be checked to ensure that the cable is properly secured, the sealing elements are intact, and the grounding is continuous (for armoured cables). The gland should also be inspected for any visible damage or loose components.
Proper tightening is essential for maintaining the integrity of the installation. Over-tightening can cause the sealing elements to deform or fail, while under-tightening can result in a loose connection that compromises the seal and grounding.
Common Installation Mistakes to Avoid
Despite the availability of detailed installation instructions, several common mistakes can occur during the installation of Hawke cable glands. These include:
- Using the Wrong Gland Type for the Cable: This can lead to poor sealing, reduced mechanical strength, or failure to meet the required safety standards.
- Over-Tightening or Under-Tightening the Compression Nut: Both can compromise the performance of the gland and increase the risk of failure.
- Incorrect Sequence of Gland Components: This can result in improper sealing, grounding, or mechanical integrity.
- Forgetting to Earth the Armour: In armoured cables, the grounding device must make direct contact with the armour to ensure electrical continuity and safety.
To avoid these mistakes, it is important to follow the manufacturer’s instructions carefully and consult technical guides and product datasheets when necessary. In addition, technical support is available from certified suppliers such as Thorne & Derrick, who can provide assistance with product selection and installation.
Additional Considerations for Special Environments
Hawke cable glands are designed to be used in a variety of environments, including hazardous and offshore conditions. The following considerations should be taken into account when installing glands in these environments:
- Corrosion Resistance: Hawke glands are available in a range of materials, including brass, nickel-plated brass, and 316L stainless steel. The choice of material should be based on the environmental conditions and the type of cable being used. For example, nickel-plated brass is often recommended for offshore environments to prevent galvanic corrosion.
- Thermal Resistance: Hawke glands are rated for operating temperatures ranging from -50°C to +80°C, making them suitable for use in extreme temperature environments. The gland must be installed in a location that does not exceed this temperature range.
- Ingress Protection (IP) Requirements: Depending on the application, the gland must provide the required level of protection against dust and water ingress. For example, an IP66 rating is often required for outdoor or high-moisture environments.
- Armour Clamping: For armoured cables, an alternative armour clamping ring (AR) is available for sizes B to F. This ring enables the clamping of armour with dimensions that fall outside the standard clamping range. The datasheet for the gland should be consulted for further clarification.
Conclusion
Hawke cable glands are essential components in industrial and hazardous environments, providing reliable sealing, grounding, and mechanical support for a wide range of cable types. Proper installation is critical for ensuring the safety, performance, and longevity of the installation. By following the manufacturer’s instructions, selecting the correct gland type, and avoiding common installation mistakes, users can ensure that their Hawke cable glands function as intended and meet the required safety standards.
For users seeking technical support or product selection advice, certified suppliers such as Thorne & Derrick offer assistance with installation, torque settings, and material selection. Additionally, the manufacturer provides detailed technical guides and product datasheets that should be consulted before installation.