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Roughing Components


Wire Reinforced PVC Hose
MDC wire reinforced PVC hose is a flexible and economical solution for mechanical pump roughing lines. They are suitable for basic vacuum service to levels of 1x10-3 Torr. The wire reinforced wall prevents tube collapse while under vacuum loads, yet provides adequate flexibility for convoluted line paths. A 20 inch minimum static radius is typical for all hose sizes. Flexible PVC wire reinforced hose is available in sizes from 3/4 to 2 inch diameters, with or without end terminations. In an nonterminated form, hose is sold by the foot to 100 feet maximum lengths. In a terminated form they are available with stainless steel Kwik-Flange™ ISO KF flanges in sizes including NW16, NW25, NW40, and NW50. The PVC hose is secured to the Kwik-Flange™ terminations via stainless steel hose clamps.

Flexible Stainless Steel Hose - Braided and Unbraided

Flexible Stainless Steel Hose
MDC flexible stainless steel hose is the perfect solution for applications where standard straight-line vacuum plumbing is not practical or where vibration isolation is required. This type of hose consists of a relatively thin wall formed stainless steel bellows which is available with an optional stainless steel braided sheath. The flexible stainless steel braiding protects the formed bellows from abrasion or impact  produced by component movement or vacuum cycling and also protects the hose from excessive bending. Both braided and unbraided configurations are offered with a choice of three end terminations including Del-Seal™ CF metal seal flanges, Kwik-Flange™ ISO KF and Large-Flange™ ISO LF flanges as well as tube end terminations.

Limited only by the choice of mount, all stainless steel hoses can be baked to 450°C. Custom sizes, lengths and terminations other than those listed are available on request. Hoses with Del-Seal™ CF metal seal flanges provide a complete metal air-to-vacuum seal required for UHV applications. Note that the large and convoluted internal surface area will require lengthy pumping to achieve UHV pressures.

Stainless steel roughing lines are available in a very flexible thin wall configuration and a less flexible medium wall configuration. Care must be taken when installing thin wall hose so as to not exceed the specified bend. MDC recommends that all thin wall hose be used primarily for vibration isolation purposes and installed with minimal bend. Flexible hoses tend to contract when subjected to internal vacuum loads. Components connected to either end of a hose must be securely anchored to prevent movement or possible damage. The total load exerted by atmospheric pressure is substantial and can move roughing pumps and other light, nonsecured components.

The static bend radius specification for a formed bellows is the minimum radius the bellows can be curved without permanent deformation. The spring rates for stainless steel flexible hose are given for reference only and are typically used as a means to quantify hose flexibility or rigidity. Spring rates are based on the amount of force required to compress one linear inch of a hose that is supported over its entire length. Since unguided hose squirms or deflects laterally, the stated spring rates are of no value unless a hose is supported over its entire length.

Small Diameter Process Lines / MDC Del-Flex™ Process Lines
MDC Del-Flex™ is the perfect solution for applications where process lines are not straight-line or where vibration isolation is required. The new process lines consist of a relatively thin wall formed 321 stainless steel bellows with 316L tube ends.<.p>

Our process lines are fully vacuum annealed to enhance cleanliness. Annealing also allows the line to be formed with a preset static bend for ease of installation. These convoluted lines are capable of manual compression and extension in length to a maximum of 20% of the nominal convoluted free length. This allows customization at installation without degrading performance integrity. The most severe static bend can be accomplished by bendingthe line until the convolutions touch at the minimum bend area and then allowing slight spring back to naturally occur, leaving the assembly in the “at rest” condition. Braided lines are available for applications where movement dynamics necessitates part contact. The braided sheath, however, does limit line flexibility.

All welds are accomplished utilizing a state of the art programmable orbital TIG welding process. During welding, argon gas is used as a purge to eliminate oxidation and ensure complete and uniform penetration. 

PVC Fittings and Components
Polyvinyl chloride, PVC components offer an economical solution for long vacuum pump exhaust lines and rough vacuum lines. PVC’s light weight and flexibility make it simple to assemble in custom configurations right on site. PVC has excellent corrosion resistance and is ideally suited for harsh chemical environments. Kwik-Flange™ ISO KF PVC components can be used in some corrosive environment applications where exposed metal surfaces are subject to chemical attack. Note that many mechanical vacuum pumps are typically supplied with ISO KF inlet and outlet ports. Kwik-Flange™ ISO KF PVC flanges are easily connected to these ports with standard centering rings and hinged clamps. PVC tubing and fittings are assembled, sealed and permanently bonded by using a PVC primer and cement.

Access Flanges
MDC Double-sided access flanges are constructed around the standard doublesided 2-3/4 inch Del-Seal™ CF metal seal flange and provide a convenient method of adding roughing accessories to a vacuum system. These flanges are offered with one or two 1/8"-27 NPT female pipe threads which accept MDC thermocouple gauge tubes and up-to-air valves or other NPT fitted components required by a specific application. These flanges can be installed in an existing vacuum system without the need for additional ports. Simply insert a doublesided flange assembly between two 2-3/4 inch Del-Seal™ CF vacuum flanges and refasten using longer bolts. Bolt kits for fastening double-sided flanges can be found in the flanges and fittings section of this catalog. Double-sided flanges are also offered with no accessory holes. Other configurations are available on request. Note that vacuum and temperature ratings for a finished assembly will be limited by the lowest rated component and by the method used to seal the pipe threads.

Up-to-Air Valves
MDC up-to-air valves are used primarily for the venting or back filling of vacuum vessels. They are vacuum rated to 1x10-8 Torr. When fitted with Del-Seal™ CF metal seal flanges they can be baked to 300°C. These are manually actuated 1/4 inch diameter valves fitted with a bellows actuator seal.

Pressure Burst Discs
Most vacuum vessels are designed and constructed with internal vacuum joints and welds that are rated for an external load of one atmosphere. They are not pressure vessels and as such should never be subjected to positive pressure loads in excess of one atmosphere. For this purpose fail-safe burst discs have been developed to prevent the accidental pressurizing of a vacuum vessel. MDC burst discs are offered with 1/8 inch male NPT fittings or Del-Seal™ CF metal seal flanges. They can be fitted to most any vacuum system where over pressurization is a possibility. The burst disc is constructed with a thin metal membrane which is capable of sustaining a vacuum load. As pressure begins to build inside a vacuum vessel, the thin metal diaphragm is deformed outwardly until it comes in contact with the sharp edges of the burst disk housing and finally ruptures, relieving the pressure in the system. Once ruptured, the unit is not reusable and must be replaced to make the vessel operational. The disc is designed to burst at a positive pressure anywhere in the range from atmosphere to 25 psig, with rupture certain to occur before 25 psig.

Leak Detector, Port Reducer Kits
MDC Test Port Reducer Kits offer a set of ten different size aluminum reducing adapters for either 1-1/8 or 2 inch leak detector inlet or test ports. They can be used with leak detectors and other devices using an internal elastomer seal. The kits provide a quick, simple, and inexpensive method for reducing standard inlets to 1, 7/8, 3/4, 5/8, 1/2, 3/8, 5/16, 1/4, 3/16 and 1/8 inch tube diameters. In the 2 inch kit, the small test ports fit inside the large adapter. Note that the 1-1/8 inch kit does not include the 2 inch adapter. Each set is supplied in a durable carrying and storage case.

Vacuum Greases and Lubricants
MDC offers a wide selection of vacuum compatible greases and lubricants ideally suited for lubricating static and dynamic elastomer seals or mechanisms in most high vacuum environments.

  • Wire reinforced PVC hose
  • Stainless steel flexible hose
  • Stainless steel braided hose
  • PVC tubes and fittings
  • Double-sided access flanges
  • Up-to-Air valves
  • Pressure surge discs
  • Leak detector, port reducer kits
  • Vacuum greases and lubricants

 Vacuum Hose and Accessories
For product listing, features and specifications click on links below
 PVC Wire Reinforced Hose
     Coiled Hose
 Flexible Stainless Steel Hose
     Del-Seal™ CF - Medium Wall
     Del-Seal™ CF - Thin Wall
     ISO KF and LF - Medium Wall
     ISO KF and LF - Thin Wall
     Weldable Hose Ends- Medium Wall
     Weldable Hose Ends- Thin Wall
 Del-Flex™ Process Lines
     Del-Seal™ CF
     ISO KF
     Weldable Tube Ends
 PVC Tubing and Fitting
     Weld Flange
     45 deg. Elbow
     90 deg. Elbow
     Primer & Cement
     Lubricant, Thread
     Lubricant, Vacuum, Dow Corning
     Lubricant, Vacuum, Apiezon
     Lubricant, Vacuum, Krytox
     Double Sided Access Flange
     Up-To-Air Valves
     Test Port Kit