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,
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.
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
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.
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.
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.