A Beginners Guide To Liquid Nitrogen Valve

Home A Beginners Guide To Liquid Nitrogen Valve
06/09/2022
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Liquid nitrogen is another form of the same element nitrogen that is too cold to be available in the liquid state. This particular form has several applications, right from cryogenic to cooling applications. Today, we are discussing some vital facts about liquid nitrogen transmission with the help of liquid nitrogen valves so that one can safely handle it. Just like gaseous and solid forms of nitrogen, liquid nitrogen is colorless and can be thus stored in a stainless 3 way ball valve. The molecules of nitrogen contained in the liquid form are pure, and they are in their liquid state as well. 

Dombor Nitrogen ​​Cryogenic Valves
Source: Dombor

Properties Of Liquid Nitrogen

Here are some of the properties of liquid nitrogen:

  • In gaseous working conditions, Boiling point is -196 degree Celsius
  • The odor of the gas None
  • Colour of the gas None
  • Taste of the gas None
  • Gas density (27°C air = 1·18g/L) 1·14

Several cryogenic valves available in the market help deliver nitrogen in its liquid form from one point to another. A portable liquid nitrogen vessel comes in handy to help the users and manufacturing units make the most of their liquid nitrogen. 

Before diving into its transmission and the operation of the valve, you must know that nitrogen has some associated risks. Hence, handling it requires a great deal of concentration and security to ensure no mishap. 

Uses Of Liquid Nitrogen

There are several applications of liquid nitrogen as it has low reactivity and temperature. Here are a few common uses of liquid nitrogen:

  • It serves as the source of very dry gas
  • It is used in crypto therapy as it helps in removing skin abnormalities 
  • It is used to transport and freeze food products
  • It is used in the cryopreservation of blood
  • It is used in cryopreservation of biological samples such as sperms, eggs, animal genetic samples, etc. 
  • branding of cattle
  • Protect items from oxidation
  • Quick freezing of pipes or water so that workers can work on them while the valves are unavailable
  • It makes ice cream, fog, flash freezing, etc.

Risks Associated With Liquid Nitrogen

Here are some of the risks associated with liquid nitrogen:

Nitrogen valve 1
Source: Alibaba.com

Asphyxiation

When boiled, liquid nitrogen produces nitrogen gas that displaces oxygen from the air, thus resulting in an oxygen deficiency in the atmosphere, especially when boiled in a closed area. One must also regularly clean the dust on the vale’s surface. Oxygen deficiency from the atmosphere can result in acute health problems. 

  • It is said to be expected when oxygen is more than 19.5%.
  • When 14% < O2 ≤ 19·5%, then there is a diminution of intellectual and physical performance without that person’s knowledge.
  • When O2 is ≤ 14%, it will result in unconsciousness, fainting, and even death in extreme cases depending on the duration and level of inadequate oxygen.

Fire 

Liquid nitrogen can condense oxygen from the atmosphere. LN2 or the liquid nitrogen creates an explosive or flammable condition by increasing the combustibility of several materials like hydrocarbons or solvents. Thus, it is the best to store this liquid in a wholesale actuated gate valve

Cold Burns

Because of the extremely low temperature, the cold gas and vapor produced when liquid nitrogen is boiled can result in frostbite or cold burns when it comes in contact with the naked skin. The exposure can also result in discomfort in breathing. Additionally, it can also lead to asthma attacks in some cases.

Ice Plug Formation Or Pressure Build-Up

Because of the high expansion ratio, if liquid nitrogen is evaporating in a closed space, it can result in pressure build-up that could result in a high risk of explosion. If there is no relief vent, ice plugs can form at the neck of the storage vessels because water is readily condensed by liquid nitrogen to form ice. All of this results in high pressure in the storage vessel. 

Let us know about the uses of liquid nitrogen to know where the valve can be used to control the transmission of liquid nitrogen. 

Application Requirements

Before using the valve of the vessel, the end user should be aware of its working or operation thoroughly to ensure that the process gets carried out as expected. Besides, you should also know the limitations of the vessel’s performance. Hence, before you order a valve for your use, you should clearly know the kind you will need. 

Different valve options are available in the market, some of which can be used for liquid nitrogen only. Other available options include those that can be used to deliver gas and liquid, whereas some can only be used to deliver high-pressure gas. That said, before making a choice, you should know the requirements of the flow and pressure of the application. The state of the medium should be known as well.  Buy the best valves from the leading industrial valves manufacturer at very affordable prices.

Nitrogen valve
Source: Indiamart

For instance, buying the valve made particularly for it would be helpful if you will only deliver liquid nitrogen. 

Sliding Gate Valves

This is one of the best-known valves that helps deliver liquid nitrogen from one point to another. The sliding gate valve is easily controllable and can be operated by anyone. This industrial gate valve is manufactured using a new approach to ensure the purpose is served. The sliding gate valve developed is light, handy, and accurate. 

The principle based on this valve excited Leonardo Da Vinci as well once. The principle is cool enough to deliver the liquid form of nitrogen from one source to another. This helps make the valve efficient enough so that it can easily handle the challenges that are placed on the control valve. 

Design Principle

The sliding gate valve is characterized by the help of a special throttle device placed in the functional unit. The valve consists of two disks in slots that get slid over each other to create a sealing effect. One of the two sealing discs gets fitted in the housing in a perpendicular position against the direction of the flow of the medium. It also has several transverse slots that are predefined. 

The second disc present is torque proof and also contains a similar arrangement of slots that gets moved in a perpendicular position to one another. This helps change the direction of flow in the cross-section way. The pressure applied moves the moveable disc against the stationary disc.

Sliding gate valves used to deliver liquid nitrogen contain several benefits. We list some of them below for the end users to know how it will benefit their application. 

  • Sliding gate valves have a long service life, attract low operating costs, and go through less wear and tear over their operating tenure. 
  • The valves also have lower weights, low actuation forces, and compact designs. 
  • The valves are straightforward because they are easy to maintain and operate. 
  • The KVS values contained by these valves are high and can be exchanged easily. 
  • While using the sliding gate valve, they have low insulation losses and also ensure reduced energy consumption. 
  • The valves attract reduced emission of noises and no sensitivity to cavitation
  • Has a high-performance cycle with very short cycle times. 
  • The valve is exceptionally tight and thereby ensures low leakage otherwise caused due to functional principle. 

Features of The Sliding Gate Valves

The sliding gate valve helps deliver liquid nitrogen, which depicts that it contains some robust features. 

  • Efficiency: One of the outstanding features of this sliding gate valve is its actuating force which amounts to only 10% of what is needed to actuate the globe valve. The size of this valve is the same as the nominal size of the globe valve and the same differential pressure. This helps ensure that small actuators can be used even though the designs of the same nominal size have the same flow rate. 
  • Vitality: The sliding gate valves are usually faster than the other conventional control valves. The same result can be displayed with the frequency response’s help when the set point value is taken as the input value. The amplitude of the resulting stroke is the same as the output value.  You can also use 3 way ball valves for the same function.
  • Cavitation: When there is a high flow rate through the narrowest cross-section of the valve, it usually lowers the local pressure. It gets lowered down below the pressure of the vapor of that liquid. This results in vapor bubbles forming, but they collapse where there is high pressure. The bubbles formed when they come in contact with the solid boundaries cause damage. 

What Are Different Types Of Liquid Nitrogen Valves 

The liquid nitrogen valves are accessible in various sizes and shapes and they are ideal for different pressure ranges. Here are some of the most common types of liquid nitrogen valves. 

  • Ball Valves 

The bodies of cryogenic nitrogen ball valves are made of polytetrafluoroethylene and they retain a higher flow rate than globe valves. They are also particularly effective when systems need a tight seal. It needs to be detected that they are simple to wear around the ball’s seals. So, their use is advised in systems having unlimited flow channels.

Additionally, they feature a vapor space high enough to permit gasification in the region under the gland. Due to the limited thermal conduction between the interior and outside of the valve, this maintains the gland packing close to the ambient temperature.

  • Top Entry Ball Valves 

This more recent variant retains a single-piece design with butt welded connections that makes maintenance simple, similar to traditional ball valves. It is a recommended solution in situations requiring fire safety due to the absence of mechanical joints.

  • Butterfly Valves 

Butterfly valves utilize a circular disc at their middle and are a member of the 90-degree turn models. This disc enables butterfly valves to be short, which makes them light in weight, less expensive, quick, and easy to operate. However, excessive use shortens their life duration. 

  • Triple-offset Butterfly Valves

In cryogenic environments, the triple offset butterfly valve is utilized to give a great performance. The seal and seat of the valve are reduced and worn down as a result of offset in these valves. This valve’s construction includes a stainless steel ring that is installed on a disc to stop leaks. 

  • Gate Valves 

In gate valves, the obturator is a wedge-shaped gate that swings to close parallel to the body seat. Even in its completely open posture, it has a minor impact on pressure. They give strong flow properties but are limited by wear and tear, much like ball valves. 

  • Globe Valves

The spherical shape of this cryogenic valve gave rise to its name. Additionally, an obturator, which is a moving disc, is present inside. It continues to rotate at a 90-degree angle in the direction of the plane, which is in sync with the body’s seat. They offer reliable long-term sealing in this way.

These valves provide better long-term sealing performance. However, they are moisture-prone and ineffective in applications where the flow rate is critical. To prevent erosion, the globe valves should be equipped with a full Stellite valve trim. 

  • Control Valves

Along with a large control range and great flow precision, the control valve has an adequate flowing capability. This cryogenic valve is mounted using a cylinder-shaped actuator or a diaphragm. Utilizing a cryogenic control valve offers certain benefits, such as its straightforward arrangement, lightweight, and resilience to regulate operations. With the low-level emission packing and stuffing box, it is possible to prolong this cryogenic valve. It contributes to the dependability and safety of the control valve. 

  • Relief Valves

In the event that the safety restrictions are exceeded, these relief valves permit steam to flee while preventing overpressure above a specific amount. The valves get pressure to a prespecified value and safeguard from over-pressurization. These valves will allow the steam to escape if the security limits are surpassed.

  • Check Valves 

The cryogenic check valve is constantly prepared to provide reliability and excellent sealing performance over a long service period. These check valves are primarily used in the LPG, LNG, and other low-temperature sectors.

Why Does A Cryogenic Liquid Nitrogen Valve Have An Extended Bonnet? 

The liquid media that the cryogenic valve transfers are flammable and explosive, including ethylene, liquid hydrogen, liquid oxygen, liquefied petroleum, liquefied natural gas, and so on. Additionally, as the temperature rises, they will gasify and expand more. This type of valve always has an extended stem, or more specifically, a vast bonnet.

The stuffing box, which is crucial to the cryogenic valve and other valves, can be protected from low-temperature damage by the expanded hood. The packing will slowly lose its elasticity and capacity to stop leaks as the temperature drops.

As the stem moves, medium freezes in the area between the filling and the stem, impeding its movement and scraping the packing. What ultimately happens is significant leakage. To assure that the packing is warm, above 8 degrees Celsius, a longer stem is utilized. 

Special substances can easily be wrapped around the valve, thanks to the vast bonnet structure, reducing cold energy loss. The “cold box” is where the pipes and valves are frequently located, but the “long neck” of the pipe can pass through the box’s wall.

Depending on that, the expanded stem makes it simple to swiftly disassemble or replace the valve’s major components through the hood. Therefore, the pipeline and valve body are joined by welding in order to minimize cold box leakage and guarantee the valve’s sealing capabilities. 

How To Choose The Right Cryogenic Liquid Nitrogen Valves 

Industrial fields like pharmaceuticals, manufacturing and freezing are increasingly using cryogenic nitrogen valves. These are mostly low-temperature working materials that are also poisonous, combustible, or explosive and have an elevated permeability. 

To assure their safe use, they must fulfill a variety of unique conditions. They retain a longer stem and an elevated packing part among these features. By doing this, the device’s internal temperature is heated less from the exterior. 

The design of the long-neck bonnet is another aspect that needs to be evaluated. It is associated with the substance’s thermal conductivity, the area of thermal conductivity, the exterior heat dissipation coefficient, and the heat exorbitance area. Utilizing an experimental method, it is estimated.

Cryogenic nitrogen valve makers must consider the materials they choose because the body of the device must endure temperature fluctuations as well as any potential development and compression motions produced, preventing the deformation of its mount.

Guide To Cryogenic Liquid Nitrogen Valve Maintenance

Maintenance is rarely necessary because the valves have a long and trouble-free lifespan. When upkeep is required, valves can be repaired on the spot. The valve handle should be turned to the “open” position.

Every 50K cycles, or every six months, these valves should be checked for appropriate operation and degradation indicators under normal operating conditions. Examinations should happen more repeatedly when operating under challenging situations.

The suggested interval for thorough valve maintenance is 500 K cycles, or every 4 years (whichever comes first). The valve body wall thickness has a mixed allowance for corrosion and erosion of 1 mm. The valve must not be utilized if this appropriation has been mechanically, naturally, or aesthetically withdrawn. 

As part of normal maintenance, fasten the gland nut by roughly 1/8 of a turn if leakage at the stem is caught. It will make up for any gland packing wear or settling. The elevated valve operating torque and increased seal wear can be caused by over tightening the stem nut.

Replacement of all seats and seals using the proper repair kit is advised if the valve is taken out of the line and dismantled. Check for wear, corrosion, or deterioration on any metallic sealing surfaces, including the ball, stem, and surfaces on end connectors that make contact with the seats. 

Instructions For Nitrogen Valve Assembly 

Here are the detailed instructions for the assembly of nitrogen valves that are in sizes 1/2″ to 2-1/2″ (or 2″ full bore). 

  • Utilizing a cloth and IPA solution, completely sterile the valve components. Apply the proper lubricant to the stem thrust seal, packing, and bearing. 
  • A stem thrust ring should be placed on the stem. With the threaded side facing up, glide the stem into the expanded bonnet and gently raise it into the bonnet bore. 
  • Put the stem seal into the stem bore while clasping the stem erect. To the stem, attach the new anti-abrasion ring, metal follower, and two disc springs. 
  • Along the stem, knit the gland nut and adjust the gland nut’s torque values.
  • By altering the nut’s orientation, attach the locking clip to the gland nut (clockwise way). 
  • Place the seal within the bottom flange of the extended bonnet. Put the stem bearing into the upper platform of the valve body.
  • Place the ball inside the body while keeping the pressure relief hole pointed in the direction of the welded arrow’s tail.
  • Slide the stem into the ball while clasping the extended bonnet.
  • Fasten the bonnet bolts and spring washers with the bottom flange of the bonnet lined up with the valve platform and the arrows on the body and bonnet pointing in an exact way.
  • Adjust the bonnet bolts’ torque levels. Knit the wrench nut onto the stem and add the handle, and serrated washer. The wrench nut should be tightened while holding the handle. 
  • Put the seats, body seals, and seat seals in the body of the valve. Fasten the bolts of the body to the torque. 
  • Allow the valve to be in the open position to flush the line. 

Final Thoughts

Delivering liquid nitrogen from one place to another will require robust and durable control valves. Also, you must ensure that the valve attracts minimal wear while picking. Furthermore, it must be compact, fast, precise, and highly reliable. As a user, you need to make sure that you purchase from a renowned seller so that they assure quality and performance.  Contact us for more information about nitrogen valves.

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