Liquid Tight Connector - Cable Gland

29, Apr. 2024

 

Liquid Tight Connector - Cable Gland

Liquid Tight Connector: Ultimate Guide for Buyers

Are you looking for some information about the liquid tight connector?

If you want to learn more, please visit our website liquid tight nylon fitting suppliers.

Perhaps you are searching about what liquid tight connector is?

Are you are aware of their different types and sizes?

What about their parts and installation?

You are in the right place.

In can be very hard finding the ideal tools and parts for your particular equipment.

The consideration not just lies in the cost of those items.

It also lies in its features and specifications.

When we talk about getting the right liquid tight connector, how do you know you are getting the best part?

In this e-book, we will present you with the necessary information you need about the liquid tight connector.

Without further do, let’s begin!

Chapter 1: Liquid Tight Connector Definition: What is Liquid Tight Connector?

In case you didn’t know yet, liquid tight connectors connect liquid tight conduit to:

  • Enclosures
  • Boxes
  • Fixtures

They are created to endure corrosive and wet environments.

Liquid tight connector installed in enclosure

They provide safe electrical service in environments that are exposed to:

  • dirt
  • oil
  • water
  • weather and;
  • other contaminants

These are available in different materials including:

  • non-metallic
  • zinc
  • steel and;
  • aluminum

They are also available in a wide variety of choices including:

  • 90 degrees angle fittings with or without insulated throats
  • 45 degrees angle fittings with or without insulated throats
  • external ground lugs
  • stainless steel wire mesh strain relief

Typical applications for liquid tight fittings include:

  • billboards
  • illuminated storefront signs
  • air conditioning units
  • robotics
  • food processing equipment
  • transformers
  • motors
  • wiring of the machine tools

These super sealtite conduit fittings safeguard conductors from any mechanical damage due to:

  • movement
  • vibration
  • seal out cutting oils, dust, water, and coolants

Liquid tight connector with metal flexible conduit

Applications like these could be seen, but aren’t limited to industries like:

  • petrochemical and chemical plants
  • petroleum refineries
  • paper and pulp mills
  • dairies
  • food processing plants
  • breweries
  • aerospace industries
  • automobile manufacturing facilities
  • paint manufacturing facilities
  • waste treatment facilities
  • electric power generating plants
  • machine tool manufacturers

Features of a Liquid Tight Connector

Some of the amazing things about the liquid tight connectors on metallic is that they are suitable for all wet locations.

They are also oil tight, rain tight, and liquid tight.

They have a very long life in corrosive, dusty, and wet settings.

Hex-shaped gland nut enables for simple wrenching.

That offers a quick and tight installation.

What’s more:

They are also reusable.

Long ferrule stops pullout and tight bend conduit pop out.

They are also the third party certified.

These are available in different sizes that range from 3/8 inches to 6 inches.

Ultimately, they are accessible in non-insulated and insulated versions to meet any client preferences.

How Does Liquid Tight Connector Work?

A stainless steel liquid tight connectors is a special electrical connector in cabling for electronic and computer systems where contaminant and water intrusion is an issue.

Its jacket is made of synthetic, plastic or rubber material, which is impervious to dust and moisture.

The jacket also offers enhanced electrical integrity and mechanical strength.

That’s true particularly in connections subject to recurrent variable and flexing temperature.

If appropriately used, liquid tight flexible metal conduit fittings can lower downtime.

It can also simplify reliability and lower the risk of an intermittent connection failure in complication systems.

For instance, blade servers, which include different cable connections, in a constrained by physical volume.

These tools could help in equipment, which is operated outdoors.

What’s more:

Liquid tight flexible conduit fittings are cheap and could last for many years.

Chapter 2: Liquid Tight Connector Types and Sizes

Did you know that there are different types of liquid tight connector?

Yes, you read that right.

Each of them has its materials too.

In this section, we will uncover the different types of liquid tight connectors and their sizes:

  • Straight liquid tight connectors
  • 90 degrees liquid tight connectors
  • 45 degrees liquid tight connectors
  • Non-metallic liquid tight connectors
  • Metallic liquid tight connectors
  • Swivel liquid tight connectors

Straight Liquid Tight Connectors

A straight liquid tight connector can attach liquid tight conduit to enclosures, boxes, and fixtures.

These type of fittings are created to withstand any corrosive and wet environments.

2 liquid tight connector are available in different sizes ranging from 1 inch to 2 ½ inches.

Straight liquid tight connector

Straight liquid tight connectors along guarantees an enduring liquid tight connector for liquid tight conduit.

Seal tight conduit fittings could serve to terminate an external bonding conductor, which runs parallel to the conduit.

Following are some of the materials used for a straight liquid tight connector

Copper-Free Aluminum

These seal tight flex connectors utilize for tough and industrial corrosive applications where aluminum is preferred.

Zinc

These 3 liquid tight connectors provide corrosion resistance from the elements

Malleable / Steel Iron

These connectors are utilized in tough, industrial and corrosive purposes.

Steel

This liquid tight flex connector boasts a tough, insulated lining to endure strain and vibration.

Nylon

These are made of a non-metallic, lightweight and non-conductive material that offers corrosion resistance.

Nickel-Plated Brass Fitting

These liquid tight straight connectors are resistant to fuels, lightweight oils, and water.

90 Degrees Liquid Tight Connector

These 90 degrees liquid tight connector can connect liquid tight conduit to:

  • enclosures
  • fixtures and;
  • boxes

These are made to endure corrosive and wet environments.

90 degree liquid tight connector

90 degrees angle models are accessible along with a protective insulated throat for conduit sizes from 3/8 inches to 2 inches.

Liquid tight straight connectors eat out:

  • dust
  • oil
  • water and;
  • other damaging particles

Following are some of the materials utilized for 90 degrees liquid tight flex conduit:

Zinc

These liquid tight to emt connector provide corrosion resistance from other types of elements.

Thermoplastic

These connectors are resistant to corrosion and abrasion in outdoor environments.

Malleable / Steel Iron

These flexible metal conduit fittings can be used for corrosive, industrial and tough applications.

Steel

This material boasts insulated, tough lining to endure strain and vibration.

304 Stainless Steel

These connectors are used in corrosive, industrial and touch settings.

45 Degrees Liquid Tight Connector

When specifications dictate bend in conduit runs, 45 degrees seal tight straight connector along with grounding lug guarantee an enduring, liquid tight connection.

45 degree liquid tight connector

It acts to terminate an external bonding conductor, which runs parallel to the conduit.

They are fabricated from robust malleable iron.

These are assembled along with an aluminum lug and steel locknut.

The 45 degrees liquid tight connector boasts an insulated throat to safeguard against conductor abrasion.

Zinc plated guarantees added resilience.

These are available for conduit sizes from 3/8 inches to 6 inches.

Non-Metallic Liquid Tight Connectors

These types of liquid tight strain relief are UV rated for outdoor applications.

Liquid tight conduit connectors are available for conduit sizes ranging from 3/8 inches to 2 inches.

No dis-assembly s needed to install here.

All you need just need to is to push the tubing or conduit over ferrule and tighten the sealing nut

No threading of conduit is needed as well.

Just lower your installed cost.

Such a watertight conduit connector might be recycled.

You can turn the sealing nut in a counterclockwise direction to release the conduit.

Some of its features include:

  • resistant to lubricants, fuels and the majority of chemicals
  • non-corrosive
  • non-conductive
  • molded 6/6 nylon

Metallic Liquid Tight Connector

This type of liquid tight fittings can avoid pullout for:

  • motion strain and;
  • stress related applications

This metal conduit fittings are perfect for hazardous locations.

This is available in 45 degrees, 90 degrees, and straight liquid tight connectors

Applications include:

  • machine tools
  • motors
  • electrical enclosures

Liquid Tight Swivel Connectors

In case you didn’t know yet:

This is the combination of 90 degrees swivel and straight swivel liquid tight flexible conduit connector.

It features a screw-on rubber PVC O-ring.

Such liquid tight connectors could be utilized along with a liquid tight conduit.

The best part about this 2-inch liquid tight conduit is that you can simply utilize one connector for all angles.

Isn’t that amazing?

Chapter 3: Liquid Tight Connector Parts

In this chapter, we will categorize the different components of a liquid tight connector and their corresponding functions.

Sealing Nut

A sealing nut for the seal tight electrical fittings is considered an inert molded elastomeric ring.

It might be reinforced internally along with an aluminum disc to remove over-compression that might take place in “O” rubber rings.

Seal

A seal is utilized to combine two parts of an engine, machine or other mechanical assemblies.

It fills the space among both parts, making a seal and filled space in the idle.

That seal stops fluid, vapor and particle leakage to safeguard and keep pressure while keeping debris out.

It also guarantees proper safety and function.

Seals are utilized in different fields and industries such as:

  • general engineering
  • aerospace
  • automotive

This is typically made of rubber.

It is position inside the body of the liquid tight connector to serve as a seal.

You see, the seal offers safe and secure coverage for the entry point of the cord and the cable.

Body

The body of the liquid tight connector has a ferrule that spreads outside the collar.

An annular ring is molded central on the ferrule.

When a non-metallic conduit is strapped into it, there’s no restraint except for the meddling fit of the annular ring.

The main body is shorter.

Thus, liquid established in the body can’t find its way to the housing.

There’s no communication between the conduit when attached to the outside of the passage and the ferrule.

Lock Nut

A locknut at the close part of the liquid tight connector is also formed along with flats to enable wrenching.

Compression Nut

There is a compression nut that features a vaulted top as well as a conical internal surface.

Throughout the installation, the conical surface triggers the clip by concluding the fingers.

The compression nut is created to bottom on the shoulder of the body.

Therefore, stopping any over torque.

Ferrule

A ferrule in the connector was threaded and often screwed into the conduit.

Chapter 4: How to Install Liquid Tight Connector

After understanding the different parts of the liquid tight conduit fittings, what’s next?

Well, it is time for you to know the proper installation.

Fitting installation is very simple.

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Take a look at the step-by-step stainless steel liquid tight fittings installation:

Step 1

Cut the conduit end square.

Step 2

You can now apply the compression nut over the conduit.

Step 3

Slip on the split gland ring.

Step 4

You must string the body ferrule end into conduit until bottomed.

Step 5

Place gland ring in contradiction of body ferrule cavity and cord the compression nut onto the body.

Step 6

Hand tightens to make sure full gripping capability.

Step 7

Break the sealing o-ring into seat given for a liquid-tight seal through some box application.

Step 8

Secure along with locknut or to threads as needed.

Conclusion

You are already aware that liquid tight flexible metal conduit connector will come in different materials:

  • nylon
  • brass
  • nickel-plated brass
  • galvanized steel
  • die-cast zinc

If you are considering buying nonmetallic flexible conduit fittings, you must understand that the NEC standard doesn’t tell which material you must be utilizing.

Alternatively, it has to meet your performance criteria.

When picking your material, you must also consider the suitability and design for your particular application.

You will find conduit materials made specifically for liquid-tight performance in the:

  • wastewater treatment
  • food and beverage business
  • petrochemical industry and;
  • other industrial applications

On the other hand, some connectors are suitable for both dry and wet application.

So make sure that when you buy for a connector for wet applications, always go for liquid-tight cord connector.

After you have identified the application and elements, which play into the setting of your connector, what’s next?

It’s time for you to look for a dependable liquid tight flex conduit fittings manufacturer.

Indeed, your task isn’t finished yet.

Fortunately, you can find a trustworthy online supplier, which provides nearly everything you need.

Make sure you select a supplier who offers that one-stop-shopping experience, so you don’t need to go to other stores.

When you purchase your liquid-tight nonmetallic conduit fittings, as well as the corresponding components to complete your installation in one place, you’re likely to get a bargain from your supplier.

If you’re in search of a reputable supplier, we’ve got you covered!

We have the best and highest quality of liquid tight connectors for all your needs!

Couplers, Hose Clamps and Fitting Selection

Fluid Coupling and Connector Selection

Choosing the Right Fluid Coupling for Your Liquid Cooling Application

Fluid line connectors are essential to liquid cooling loops. Engineers must consider selection, installation, and maintenance of a system’s fluid connections to prevent leaks and ensure system longevity.

As there are a plethora of fluid connector options available, it can be difficult to decide which one works best for your application. Liquid cooling fluid connectors typically fall into two categories: fittings and couplings. Part 1 of this article discussed fittings. This part will review the two factors to consider when selecting fluid connectors and will describe the most common types of couplings used in liquid cooling applications.

I. Assessing the Application

Understanding your application is critical in determining which coupling is the best for your liquid cooling system. Some questions you should ask when considering couplings include:

What is the system fluid?

Is the fluid’s viscosity and corrosiveness compatible with the system hardware? Understanding how changes in the coolant’s viscosity over the operating temperature range can impact the pressure drop across the fluid connectors. Check to make sure the fluid is chemically compatible with the fluid connector’s wetted materials including any O-Rings. (Learn more about some of the most common O-Ring compounds

What are flow rate requirements?

This impacts your tube or hose selection and therefore coupling requirements. The internal diameter of the fluid path components will have a great impact on pressure drop and fluid velocities. Account for pressure drop across connectors and check fluid velocities to prevent erosion corrosion. (For more information on erosion corrosion please see our application note “Erosion-corrosion in Cooling Systems“.

What operating range will the system experience for temperature and pressure?

Connectors need to maintain the seal at all these operating points. Ensure that hose or tubing wall thickness, surface finish, hardness or durometer, concentricity, and ovality can withstand expected pressures and temperatures.

Will the system experience vibration, pulsation, or thermal cycling?

Seals between the fluid connector and hoses must withstand these extreme condition changes.

How is the coupler mechanically integrated into the system?

Common mounting options include pipe thread, in-line, rigid mount, panel mount, or elbow.

Do you need to comply with specific industry standards or other special requirements?

International Standards Organization (ISO), Food and Drug Administration (FDA), and Restriction of Hazardous Substances (RoHS) are common standards many applications must adhere to. Sterilization, color coding or labeling, and specific packaging requirements are other common specifications to consider when selecting couplings and connectors.

II. Determining the Type of Fluid Connector

Fluid connectors can be considered either fittings or couplings, which are common hardware components in a liquid cooling system. Both connect cooling loop components such as valves, pumps, liquid cold plates, heat exchangers, hoses, etc. Fittings and couplings are differentiated mainly on how they are used in a system.

Fittings are used when disconnection of equipment is infrequent, since repeated removal can cause leaks. Fittings are relatively less expensive compared to couplings and come in many different sizes, types, and materials. Fittings require tools for installation and removal.

A coupling enables quick connection and disconnection a line without fluid loss or introducing air into a system. A coupling is a better fluid connector for systems that require fast assembly or routine maintenance. For example, modular equipment like a liquid-cooled chassis requires quick disconnect couplings (QDC) in order to be serviced or maintained on the field, especially for military applications (See Figure 1).

Couplings come in a variety of materials, including plastics such as acetal and nylon, which are cost-effective and compatible with a wide range of fluids. Plastic can also be molded into a variety shapes or include colors to distinguish between different fluid lines. Metal couplings are used in more challenging environments where shock and vibration, higher pressures, weight, temperature variations, personnel safety, and other challenging requirements call for greater durability and strength.

Quick Disconnect Couplings Types

There are basically four types of quick disconnect couplings used in liquid cooling applications. They are straight through, single shut-off, double shut-off, and non-spill.

Straight-Through Couplings

The simplest type of coupling is a straight-through coupling (See Fig. 2). These couplings do not have any internal valves to obstruct fluid flow so they provide minimal pressure loss. External manual shut-off valves are required to prevent fluid loss when disconnecting. Straight-through couplings normally have operating pressures of up to 5,000 psi. This type of coupling is typically used in applications where the loss of coolant when breaking the liquid cooling loop can be tolerated.

Single Shut-Off Couplings

Also known as one-way shut-off couplings (See Fig. 3), they consist of a check valve, usually on the female half and no valve on the male mating half. These types of couplings are normally used in applications where leakage or spillage of the fluid on the downstream side of the system is not as important. They are normally installed with the valved half on the pressure side of the circuit to provide automatic shut-off when the coupling is disconnected. Single shut-off couplings are generally suited for working pressures of 60 to 300 psi. (Note that couplings’ maximum pressures depend on design and material.

Double Shut-Off Couplings

Double shut-off couplings (See Fig. 4), also known as two-way shut-off couplings, have a check valve on both the male and female halves. They are used in applications where downstream leakage or spillage is undesirable. This type of coupling is generally capable of much higher pressures than single shut-off couplings. Double shut-off couplings can support applications with pressures up to 10,000 psi.

Non-Spill Couplings

This variation of a two-way shut-off coupling, also known as flat face, dry break, or non-spill coupling (See Fig. 5), is a two-way shut-off coupling designed for applications where any leak or spillage poses a risk of contamination. The internal valve configuration prevents any loss of fluid upon disconnection and minimizes air entry when connecting. This type of fitting usually has operating pressures of up to 5,000 psi.

As with the fittings we discussed in Part 1 of this article, there are many coupling options available, so it is very important to understand your application requirements in order to have a reliable and serviceable liquid cooling system. To ensure you choose the right fluid connector for your application, it is best to work closely with your coupling or liquid cooling components partner early in the design process.

Fluid Fitting and Connector Selection

Choosing the Right Fluid Connector for Your Liquid Cooling Application – Part 1: Fittings

Fluid line connectors are critical in liquid cooling applications. Selection, installation, and maintenance of a system’s fluid connections are all important in preventing leaks and maintaining system integrity. With so many fluid connector options available, it is often difficult to decide which one is best suited for your application. The two main types of fluid connectors found in liquid cooling applications are fittings and couplings. Part 1 of this article will cover two important factors to consider when selecting fluid connectors. It also will describe the types of fittings most frequently used in liquid cooling applications.

I. Assessing the Application

The key in selecting the right fluid connector is understanding your application. Here are some of the questions you should ask:

What is the fluid media? Viscosity and corrosiveness of the fluid must be considered. Understand how changes in the coolant’s viscosity over the operating temperature range can impact the pressure drop across the fluid connectors. Make sure the fluid is chemically compatible with the fluid connector’s wetted materials including any O-rings.

What are the tube or hose size and flow rate requirements? The internal diameter of the fluid path components will have a great impact on pressure drop and fluid velocities. Make sure to account for pressure drop across connectors and check fluid velocities to prevent erosion corrosion.

What are the maximum and minimum system operating temperatures and pressures? Connectors will need to maintain the seal at all these operating points. Consult with your fluid connector supplier for the proper hose or tube wall thickness, surface finish, hardness (durometer for hoses), concentricity, and ovality (tubing only).

Will the system experience vibration, pulsation, or thermal cycling? The seal between the tube or hose and the fluid connector needs to be maintained during these changes in process conditions. Check with your fluid supplier for the proper fluid connector for your application.

How is the connection going to be configured into your application? Common mounting options include pipe thread, in-line, rigid mount, panel mount, or elbow.

What industry standards or other special requirements need to be complied with? Some standards to consider include ISO (International Standards Organization), FDA (Food and Drug Administration), and RoHS (Restriction of Hazardous Substances).

II. Determining the Type of Fluid Connector

Fittings and couplings are the two main types of fluid connectors commonly used in liquid cooling applications. Both are used to connect cooling loop components such as valves, pumps, cold plates, heat exchangers, hoses, etc. Fittings and couplings are differentiated mainly on how they are used in a system.

A fitting is typically used in applications that do not require the frequent disconnection of equipment or parts, since repeated removal can cause leaks. Fittings are usually inexpensive compared to couplings and come in many different sizes, types, and materials. Fittings also require tools for installation and removal.

A coupling provides a means of quickly connecting and disconnecting a line without a loss of fluid or entrance of air into a system. If equipment needs to be assembled quickly or if it needs routine servicing or repair, then a coupling is a better choice for a fluid connection. For example, equipment designed in modules, such as liquid-cooled chassis used by the military, requires quick disconnect couplings (QDC) in order to be serviced or maintained on the field. (See Figure 1).

Couplings come in a variety of materials, including plastics such as acetal and nylon, which are cost-effective and compatible with a wide range of fluids. Plastic can come in a variety of colors to distinguish between different fluid lines. Metal couplings are typically used in more challenging environments where shock and vibration, higher pressures, weight, temperature variations, personnel safety, and other challenging requirements call for greater durability and strength.

Fitting Types

Beaded Fittings

This fitting consists of a straight tube that has a bead around its outside diameter, as shown in Figure 2. An interference fit is used between the internal diameter of the hose and the outside diameter of the fitting to seal the connection. The clamp provides the force to maintain the seal and retain the hose. Beaded tubes are made per U.S. Military Standard MS33660 or per Aerospace Standard AS5131. Proper bead design as well as proper clamp and hose selection are critical in providing a leak-tight connection. Refer to our Fitting and Hose Clamp Selection for Cold Plates and Heat Exchangers application note for more detailed information on beaded fittings.

Barbed Fittings

As with beaded fittings, barbed fittings are used with hoses. Barbed fittings (See Figure 3) are fluid connector devices that have one or more continuous ridges that grip and seal the inside diameter of the hose. Slope and depth of the barb, sharpness of the gripping edge(s), number of barbs, and their spacing, all play a part on how well the fitting grips and seals. Refer to “Don’t be too casual pairing tubes to barbed fittings1” for more detailed information on barbed fittings.

NPT (National Pipe Thread) Fittings

These fittings have tapered internal or external threads (See Figure 3). The seal on these fittings occurs between the flank, crest, and root of the two joining metal surfaces. Because galling and tearing of the joining metal surfaces can occur during installation, it is imperative to apply a lubricant or sealant on the male threads to prevent damage. A popular thread sealant is PTFE (polytetrafluoroethylene) tape. NPT fittings are common fluid connections for cooling systems such as recirculating chillers and for cooling components such as brazed plate liquid-to-liquid heat exchangers. A good reference on how to make reliable pipe thread joints is “Pipe Thread Types and Designations”.

SAE (Society of Automotive Engineers) Threaded Fittings

SAE straight threaded fittings are designed to provide retention via the threads. They do not provide a metal-to-metal seal like NPT fittings. Sealing is provided by an O-ring, generally located at the base of the male thread. (See Figure 4). This type of threaded fitting offers advantages over an NPT connection in that maintenance, accessibility, and remake of the fitting are significantly easier. It also offers an advantage over compression fittings that are typically tightened within a higher, yet narrower torque range, which makes it easier to strip the threads and crack or distort fitting components and cause leaks. The rubber-to-metal seal provides a “feel” when the operator tightens the fitting. O-ring fittings tend to be more expensive than their all-metal counterparts and care must be taken when installing the fitting so that the O-ring does not get damaged or fall out of the groove. Selecting the wrong O-ring or reusing one that has been deformed or damaged can cause leaks.

Compression Fittings

A compression fitting is comprised of three components: a threaded nut, body, and ferrule or olive (see Figure 5). When the nut is tightened, it compresses the ferrule, causing it to conform to the circumference of the tube. To work properly, the ferrule must be oriented correctly. One advantage of this type of fitting is that no special tools are required during assembly. Some of the disadvantages are that it comes in limited materials (brass or copper) and can handle minimal pressure compared to flare, bite-type, or mechanical grip type fittings (see below). A compression fitting is not recommended for applications having vibration, thermal cycling, or other dynamic forces.

Flare Fittings

A flare fitting is also made up of three components: a nut, sleeve, body, and rigid tube with a flare, as shown in Figure. 6. Metal-to-metal sealing takes place as tightening of the nut draws the fitting into the flared end of the tubing. This type of fitting typically can handle higher pressures than a compression fitting and it requires tooling to flare the tube-end in preparation for installation. Improper flaring of the tubing can cause axial cracks on thin or brittle tubing. Care must be taken when cutting the tube, since poorly designed tube cutters or ineffective hacksaws will create an uneven sealing surface.

There are several types of flare fittings. There is the 45º JIC flare, which is often used in lower pressure applications such as fuel lines and HVAC applications. A commercial grade 37º flare fitting, better known as a 37º JIC flare fitting, is manufactured to SAE-J514/ISO 8434-2 standard and uses a UNS (Unified Thread Standard) class 2A/2B straight thread. Another type of 37º flare fitting is the 37º AN flare fitting, which is manufactured to MIL-F-5509 per AN (U.S. Air Force/Navy standard).

Although these two 37º fittings are compatible with each other, the 37º AN flare fitting uses a tighter UNS, Class 3 tolerance on the threads, allowing a 40% increase in fatigue strength. This is why 37º AN flare fittings are about three times more expensive than similar SAE/JIC 37º flare fittings. Since one cannot visually determine one from the other, AN 37º flared fittings are marked with an MS or AN marking per MIL-P-5509D, and can also be differentiated by the way they are specified in writing. For example, they might be specified as “AN fitting: ½-20 UNJF-3B, SAE/JIC fitting: ½-20 UNF-2B.”

Bite-Type Fittings

Similar to other compression fittings, a bite-type fitting has a threaded nut, body, and ferrule(s). On a single ferrule fitting (See Figure 7), the leading edge bites into the surface of the tubing to achieve holding ability. The seal is made on the long, deep surface between the ferrule and the internal taper. Typically, bite-type fittings are of single ferrule design. On a two ferrule design, the first ferrule provides the sealing and the second ferrule provides the retention. The spring-like action of the ferrule(s) during installation compensates for the variations in tubing material and hardness, as well as the thickness of the wall tube and temperature variations. This provides a leak-tight fluid connection for an extensive range of applications.

Mechanical Grip-Type Fittings

A mechanical grip-type fitting is comprised of a threaded nut, body, and two ferrules. The difference with the two ferrule bite-type fitting discussed previously is that a mechanical grip-type uses the back ferrule to spring load the front ferrule as it seals by coining the surfaces of the tubing and coupling body (see Figure 8). Another difference over the bite-type fitting design is that break and remake of this fitting after installation can be better accomplished without damage to either the fitting components or the tubing.

O-Ring Face Seal Fittings

An O-ring face seal fitting consists of a threaded fitting body with O-ring groove, O-ring, threaded nut, and sleeve or tailpiece. The fitting assembly seals when the tailpiece, which is permanently brazed or welded to the tube, compresses the O-ring on the face of the threaded fitting body as the nut is threaded onto the external threads on the fitting body. (See Fig. 9). This fitting is a “zero clearance” system because you do not need to spring or pull the tubing in order to seat the fitting or purge the system. This tube fitting can be disassembled and reassembled many times. Simply replace the O-ring and tighten to manufacturers’ recommended torque. The O-ring conforms well to sealing surface irregularities. These types of fittings are recommended for high vibration applications because the O-ring absorbs shock better than any metal-to-metal sealing system.

With so many fitting options available, it is critical to understand your application as well as the frequency of connection and disconnection required. The reliability and serviceability of your system depends on the fitting selected. To ensure you choose the right fitting for your application, it is best to work closely with your fitting or liquid cooling components partner early in the design process.

Fitting and Hose Clamp Selection for Cold Plates and Heat Exchangers

Determining the Best Way to Prevent Flexible Hosing Leaks

The selection of the proper fittings and hose clamps for cold plates and heat exchangers is critical to a reliable liquid cooling system. It can prevent unnecessary downtime and equipment damage. Based on over 50 years experience with scores of fittings and clamps in hundreds of applications, we have found two options which have proved to be superior. Below we discuss the use of beaded fittings and the advantages and disadvantages of the two preferred clamp options.

When a system requires flexible tubing, the beaded tube fitting has been specified almost universally, especially in critical applications such as computer, medical, laser and automotive where operation must be 100% leak free. The bead, a 0.035″ +/-0.003″ ridge for 0.375″ OD tubing (See Figure 1), prevents the clamp and hose from slipping off the tube; the bead does not prevent leaks, however.

The clamp prevents leaks at the joints. The clamp sealing performance, defined as the static pressure and tightness, depends on several factors:

  • The material and design of the hose
  • The compatibility of the hose bore to the connecting part
  • The correct selection and installation of the clamp
  • Various mechanical factors such as pressure, temperature, and vibration

Boyd recommends two types of clamps, the ear/crimp clamp and the worm or gear clamp. The ear clamp, shown below in Figure 2, is a metal band that is crimped with a special tool to form a leak-free connection. The worm clamp, Figure 3, consists of a notched band with a screw mechanism to loosen or tighten the clamp.

Each clamp has advantages and disadvantages as determined by your application. See Table 1 for a comparison of features.

Table 1: Clamp Comparisons of Features

Ear Clamp

Worm Gear Clamp

Superior clamping performance

Standard clamping performance

Circular, uniform clamping pressure

Some have flat spot under tightening mechanism

Shows tampering

Does not show tampering

Not reusable

Reusable

Special tool required for installation; hand tool or pneumatic tool (recommended)

Standard screwdriver required for installation

Can be difficult to install (crimp) in tight places

Can be installed in tight places

Ear Clamps

Ear clamps provide superior sealing because the connection cannot loosen over time. Since ear clamps have a low spring constant, Hooke’s Law dictates that ear clamps maintain a greater force after hose relaxation. They maintain a circular geometry after tightening which proves more reliable. Installation is simple, the ear clamp slips over the hose fitting joint and requires a pneumatic or hand tool to tighten. We strongly recommend the pneumatic tool because it insures consistent pressure applied around the fitting and greater consistency in a production environment. Also any tampering is visible with the ear clamp.

The drawback of the ear clamp is that it can only be used one time and it requires a crimping tool for field replacement. The crimping tool can be bulky and difficult to use in tight places. These three disadvantages limit the ear clamp’s serviceability.

Worm Clamps

The worm clamp has its own set of issues. Some designs have a flat spot below the screw mechanism that can result in uneven pressure around the fitting. However, many worm clamp vendors have new designs that eliminate the flat spot. In addition, worm clamps tend to be stiff so a slight hose relaxation can result in a significant loss of force. In the past the notches for the screw mechanism would cut into the hose and could be a potential leak source. Again, new designs include a smooth inner surface.

The chief advantage is greater system flexibility and serviceability. The worm clamp is easily replaced in the field with just a screwdriver. And thanks to its wide diameter range, the same clamp can be used with a variety of hose sizes. The correct choice of materials and the availability of many band sizes make the worm clamp ideal for low and medium pressure applications.

Hose Clamp Selection Conclusions

Let your performance requirement guide you. In the end, the best fitting/clamp combination will be determined by your performance goals. If leak integrity is paramount and high cooling liquid pressures are involved, the ear clamp is appropriate in most cases. When easy field maintenance is the key factor and liquid coolant pressures are low to medium, the worm clamp/beaded fitting combination will serve you best. If you still have questions about your specific application, consult your clamp manufacturer. With the proper fitting and clamp, your liquid cooling loop will provide years of leak-free operation.

Choosing Quick Disconnect Couplers

Considerations for Selecting the Right QD for your Application

In order to select an optimal quick disconnect, start first with a thorough understanding of your assembly, application and operating environment.

Temperature:

  • What are the minimum and maximum operating temperatures? Based on selected coupler material, common temperatures range from -40º F to 200º F.

Pressure:

  • Know the operating pressure range the quick disconnect will be exposed to. Confirm that the quick disconnects maximum pressure rating will not be exceeded by your application.

Media:

  • What fluid will be used in the system? Check the fluid’s viscosity and corrosiveness; confirm chemical compatibility of the fluid with the quick disconnect system.

Shutoff Options:

  • There are a variety of shut off options. Consider what shut off options meet the needs of your application: single-sided, double-sided, non-spill, automatic, or integral shutoff valves.

Flow:

  • Know your application’s required pressure drop and gallons per minute (GPM). In your flow calculations, consider full system impact including the effect of shutoff valves and tubing connections.

Tubing:

  • There are a wide variety of tubing sizing, both inner and outer diameter. Know what size is specified in your application and confirm chemical compatibility with selected fluids.

Tubing Connections:

  • Know your tube connection type. Are you using hose barb, compression fittings, push-to-connect or some other less common termination style?
  • Know your tube connection size. Properly match tube inner diameter for hose barbs. For push-in fittings, properly match outer diameter. For compression fitting, match both tube inner diameter and outer diameter.

Mounting Options:

  • How have you designed your quick disconnect to fit and function within your custom application? There are a wide variety of options to mount your quick disconnect: pipe thread, panel mount, in-line or elbow.

Special Requirements:

  • Do you have additional special requirements? Cleanliness requirements or sterilization? Specialty material specifications like NSF approved or USP Class VI approved? Do you have custom finishing requirements like special packaging, color coding, keying or lot traceability?

Most importantly when specifying a quick disconnect consider serviceability, replacement availability and processes as well as ease of installation.

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