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What is the difference between mechanical seal and dry gas seal?

What is the difference between mechanical seal and dry gas seal?

Dry gas seals are mechanical seals but use other chemicals and functions so that they do not contaminate a process. These seals are typically used in a harsh working environment such as oil exploration, extraction and refining, petrochemical industries, gas transmission and chemical processing.

What type of ring is used in a dry gas seal?

A dry gas seal consists of a rotating, hard-face mating ring with either a machined or etched circumferential spiral groove pattern and a primary (stationary) ring in softer ma- terial. The primary ring is radially restrained but can move in the axial direction.

What are dry gas seals used for?

Dry gas seals use a separation seal on the bearing side of the seal as a barrier. The purpose of the barrier seal is to prevent lubricating oil from migrating along the shaft and into the dry gas seal. This seal also prevents any gas leakage from the dry gas seal from leaking into the bearing cavity.

What is tandem dry gas seal?

Tandem Dry Gas Seal with Labyrinth This seal is used in applications where the product leakages to the atmosphere as well as buffer gas leakages to the product are inadmissible, for example, on H2, ethylene or propylene compressors.

How do you install dry gas seal?

Carefully study the installation drawing. All devices that secure the gas seal stator or rotor to the compressor casing or shaft must be removed. Install the seal installation plates as identified on the installation drawing. Install the special tools (removal purpose) as provided by the compressor manufacturer.

What is dry gas made of?

Dry gas typically contains either methanol or isopropyl alcohol. Most gasoline now contains around 10-15% ethanol solution.

What is the difference between dry seal and Wet seal?

Dry seals require a gas console, filtration unit, controls, and monitoring instruments, while wet seals require the seal oil pumps, fan coolers, degassing unit, and controls.

What is the difference between Wet seal and dry seal?

How many sealing faces does a tandem seal have?

These seals often use two rotating seal faces and two stationary seal faces. A fluid is provided between these two seals at a lower pressure than the sealed fluid (known as buffer fluid) or at a pressure higher than the sealed fluid (known as barrier fluid).

Does dry gas expire?

In general, pure gas begins to degrade and lose its combustibility as a result of oxidation and evaporation in three to six months, if stored in a sealed and labeled metal or plastic container. Ethanol-gasoline blends have a shorter shelf life of two to three months.

Why is it called dry gas?

As applied to determination of heating value or specific gravity dry gas means the complete absence of moisture or water vapor. Dry Gas means Natural Gas containing essentially methane, ethane and inert gases. Dry Gas means Gas that is not Wet Gas.

What is reference gas in compressor?

The reference gas is the process gas inside the compressor. Its pressure is usually balanced from the discharge seal to the suction seal so both seals are operating at the same pressure.

What is seal gas in compressor?

The seal gas used as the sealing medium is usually a clean, dry and cool gas that is compatible with the process gas being compressed. The seal gas supply pressure MUST be a higher pressure than the compressor seals will ever encounter.

Why is double balance important in dual seals?

Double-balance-line feature allows seal to work with pressure from either direction. i.d., inside diameter. Source: Flowserve. The use of dual seals, such as API Arrangement 2, with a low or unpressurized buffer is familiarly known as a tandem arrangement.

What’s the difference between single and double mechanical seals?

A single seal has two faces, while a double seal has four. A double seal divides faces into rotating and stationary. Single seals use the pump’s fluid as a lubricant, while double seals have a dedicated buffer or barrier liquid.

Is dry gas needed anymore?

Dry gas is not really a necessary part of routine maintenance, but if there is any reason to suspect that a vehicle is suffering from water-contaminated gas, especially in the winter, dry gas is an excellent solution.

Is 10 year old gas still good?

Degradation occurs from the get-go but most gas stays fresh for a month or two without issue. However, gas that is more than two month old is generally OK to use with only minor decreases in performance. Gas that is older than a year can cause issues, like engine knocking, sputtering and clogged injectors.

What is buffer gas seal?

This seal is used when a neutral buffer gas of suitable pressure is available. Typical applications are to be found mainly in the chemical industry, for example, on HC gas compressors. A buffer gas, for example, nitrogen, is fed between the seals at a higher pressure than the product pressure.

Why nitrogen is used as seal gas?

Nitrogen is used for pressurizing dry gas seals on selected gas compressor and gas turbine installations that need inert gas for lubricating and pressurizing dry seals designed to contain flammable, toxic, or hazardous process gases from leaking into the atmosphere.

What is the difference between barrier fluid and buffer fluid?

As defined in API 682, a buffer fluid is used in unpressurized dual seals. A barrier fluid is used in pressurized dual seals to isolate the pump process liquid from the environment. Gases may be used as buffer or barrier fluids depending on the design of the mechanical seals.

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