Seal Groove Research Articles

Geometry and contact pressure of an O-ring mounted in a seal groove

This paper gives equations that are useful in engineering practice to determine the geometry, the contact pressure, and the force of the contact pressure of an O-ring mounted in a seal groove loaded and unloaded by the sealed pressure. The equations were verified in line with the present state of the art in this field and taking into account modern analytical methods. The information on the geometry, the contact pressure, and the force of the contact pressure is useful in resolving the problems of leak tightness, friction, leakage, durability, and also design of the O-ring seals

Model Testing of an Oval-Shaped Seal for Sealing of Large Gaps Between Mating Surfaces

A pressure chamber was designed and manufactured in two parts, which were clamped together at their flanges using a clamping ring. An "O" ring seal was used for sealing the gap between the mating surfaces. The clamping ring held the two flanges together while the chamber was pressurized with mixed gas. The internal chamber pressure caused the gap to widen (unseat with pressure), resulting in a final gap in which the O-ring could no longer maintain an adequate seal. The O-ring seal groove was designed with an undercut or dove-tail groove to capture the O-ring. The dovetail groove cross-sectional area was designed to accept 100 percent of the O-ring area. The pressure chamber could not be taken out of service to redesign the mating connection and to accomplish the related production work. To solve this problem, an oval-shaped seal was designed to fit into the existing dovetail groove, but with a greater standoff height to allow for the larger gap (Fig. 1).Fig. 1Pressure chamber assembly

Ceramic turbomolecular pumping system in reactor structure of FER

Abstract A new pumping system consisting of ceramic turbomolecular pumps and their ceramic fore-pumps has been studied as the main pumping system of FER since these pumps have been developed at JAERI recently. The turbomolecular pump has a rotor of silicon nitride, which is driven by a gas turbine, oil free gas bearings and a non-contact spiral groove seal. The effects of neutron radiation, heat loads and magnetic fields on the ceramic pumps are evaluated based on the FER design conditions.

Experimental Study on the Static and Dynamic Characteristics of Screw Grooved Seals

Screw grooved annular seals are used in many heavy duty pumps such as boiler feed pumps. These annular seals have a significant effect on rotordynamic characteristics of the pumps. Studies on the dynamic characteristics of plain and circumferentially grooved annular seals have been published by many researchers. However, published works on screw grooved seals are few, and pump designers have not fully recognized the basic characteristics of screw grooved seals. Extensive experimental studies have been conducted for determining the basic characteristics of screw grooved seals. The leakage characteristics, load capacity, and dynamic characteristics for rotordynamic analysis were determined by using a specially designed test facility and test method. The test results were compared to the results of plain seals [3] and the basic differences were extracted for effective application of screw grooved seals.

Analysis for Rotordynamic Coefficients of Helically-Grooved Turbulent Annular Seals

An analysis for helically-grooved turbulent annular seals is developed to predict leakage and dynamic coefficients, as related to rotordynamics. The grooved surface pattern is formulated as an inhomogeneous directivity in surface shear stress. The governing equations, based on both Hirs’ turbulent lubrication theory and “fine-groove” theory, are expanded in the eccentricity ratio to yield zeroth and first-order perturbation solutions. The zeroth-order equations define the steady-state leakage and the circumferential velocity development due to wall shear for a centered rotor position. The first-order equations define perturbations in the pressure and axial and circumferential velocity fields due to small motion of the rotor about the centered position. Numerical results are presented for proposed grooved seals in the High Pressure Oxygen Turbopump (HPOTP) of the Space Shuttle Main Engine (SSME) and for a water-pump application. The results show that an optimum helix angle exists from a rotordynamic stability viewpoint. Further, a properly designed helically-grooved stator is predicted to have pronounced stability advantages over other currently used seals.

A study on the dynamic characteristics of pump seal (2nd report, in case of parallel grooved seal)

A study on the dynamic characteristics of pump seal (2nd report, in case of parallel grooved seal)

Hydrostatic Seal Design

The literature contains numerous references to applications where the designer has utilized the advantages of non-contacting hydrostatic seals to solve problems of operating under conditions of high speeds, pressures and temperatures. Examples vary from gas designs for turbines and compressors to liquid applications such as boiler feed pumps and liquid-sodium pumps for nuclear reactors. It is the view of the authors that this type of seal, proved under these very difficult operating conditions, has considerable advantages when compared to ‘balanced’ mechanical face seals. In this paper, the principles of operation of hydrostatic seals are presented and design data are given for orifice-, capillary- and slot-controlled designs, including a comparison of their performances under variable-temperature conditions. A method for optimizing the location of the seal groove is presented.

Pressure fluctuations in vacuum systems

Some of the pressure fluctuations or pips in vacuum systems are shown to originate at the regular sealing surfaces of elastomer gaskets and not to be caused by oil films at the lip of the seal groove. The fluctuations are virtually absent with greased gaskets. They increase as the surfaces are freed from oils and greases. The joints giving the pips can be located by observing the decrease in pip frequencies as the joint is cooled and sometimes by use of a leak detector.

On the Characteristics of the O-ring Packings : 1st Report, Oil Leakage from an O-ring Packing Used for the Gascket Packing

One of the most persistent problems in the design of hydraulic systems is sealing of the operating fluid in many types of machinery. Synthetic-rubber O-ring seals is being used successfully for the static, reciprocating and rotating pistons. In this report, the authors have experimentally investigated the oil leakage from an O-ring Packing used for the gascket packing. The results are : 1) O-ring must be radially compressed between the bottom of the seal groove and the cylinder wall or the flat plate for proper sealing action. This compressive force is proportional to the 4.5th powers of the J.I.S. hardness of O-ring materials. 2) The seals can be made perfectly leakproof for static conditions for oil pressure up to 280 kg/cm2 (limit of test pressure) 3) According to the "self-sealing principle" and the experimental results, O-ring can be used for the collar instead of the seal groove. 4) In order to withstand the high pressurers, setting of the O-ring packings are designed so that cover plate have no deflection in the working state.