McAllister Technical Services
Manufacturers of surface analytical instruments and devices

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Differentially-Pumped Rotary Platform (DPRF)
Instructions and User's Manual

                  THANK YOU for your purchase of MTS' Differentially Pumped Rotary Platform (DPRF). It is the finest of its kind available. We appreciate the confidence you have placed in our company. We encourage your comments and suggestions on this product and its manual. Please read this manual carefully prior to assembling/mounting your DPRF. We have found this will answer many of the commonly asked questions, saving time and aiding understanding. It will be time well spent.

Check for Shipping Damage:

                  Many shipping companies require that claims for damage and/or loss be filed within a very short period of time, sometimes within one week of delivery! Promptly inspect the shipment for exterior as well as hidden damage. If any damage or loss is encountered, be sure to do ALL of the following:

1. Notify the shipper promptly. If the damage is significant, insist on an on-site inspection.
2. Retain ALL packing materials.
3. Do not proceed with installation or unpacking.
4. Do not allow the shipping company to remove the goods from your premises without first notifying MTS.

                  Verify the shipment received against the enclosed packing list and against your order. Notify MTS promptly of any discrepancies. Clean any debris, dust or stray packaging material from the DPRF before removing the flange covers. Check for any loose screws.

Unpackaging Instructions:

                  Inspect the unit for hidden damage from shipment. Our products are shipped with custom foam-in-place packing. We have found this to be the best way. The foam is separated approximately halfway inside the carton with thin white plastic. The unit is also bagged in polyethylene, and the flanges are covered with aluminum foil and plastic covers. The flanges are capped to prevent damage. All of this is designed to get the unit to you in the same condition it left our shop. We recommend you save the packing box and materials, if possible, for equipment or possible future shipment.

1. Take the device out of the box on a clean surface.
2. REMOVE THE SHIPPING CAPS COMPLETELY! Be sure to save them for later use. The device is now ready for installation.
3. Do not allow contamination to get into the interior.

General Precautions:

                  Under normal conditions your DPRF will provide years of trouble-free service, especially if the following simple maintenance is performed. After several bakeouts, it may be necessary to relubricate the worm shaft. Use the MoS₂ grease in the supplied syringe. The worm drive can be removed for easier access. When replacing the screws in the bracket or any other location on the manipulator, be sure to re-coat the threads with an anti-seize compound.

                 The only metal components exposed to vacuum are type 304 stainless steel and 6061 aluminum. There are two differential pumping volumes, isolated by three fluorocarbon seals. These volumes are pumped through the 1.33" OD mini-ports located at the perimeter of the seal.

                 Linear and lateral alignment is maintained by a special ball bearing made of hardened carbon steel. This bearing will corrode. Do not allow moisture to condense on, or in, the bearing. Do not allow LN₂ to chill the seal. To prevent moisture, dust and/or debris from entering the bearing, there is a fourth seal to protect it. (This feature is unique to MTS differentially pumped rotary platforms.)

                  Use the appropriate bolts, washers and gaskets to mount the device to your chamber. Use standard, 0.080" thick, flat copper gaskets. For the tapped flanges, use the bolt sizes recommended in the following table for installation. Double check that your mating equipment has standard thickness flanges. These recommended bolt lengths are for standard thickness ConFlat type flanges. USING INCORRECT LENGTH BOLTS FOR INSTALLATION CAN DAMAGE THE DPRF ASSEMBLY. The bolts may be supplied by you, or you may use a DPRF bolt set available from McAllister Technical Services. The standard DPRF-series platform uses the following bolt sizes:

Model		Nominal Flange Size		Bolts SAE (Metric) Sizes
DPRF275		2.75" (70 mm)		1/4-28 X 7/8 & 8-32 X 1/2 (M6 X 1 X 20 & M4 X 0.8 X 15)
DPRF450		4.5" (114 mm)		5/16-24 X 1-1/4 & 8-32 X 1/2 (M8 X 1.25 X 30 & M4 X 0.8 X 15)
DPRF600		6.0" (150 mm)		5/16-24 X 1-1/2 & 8-32 X 1/2 (M8 X 1.25 X 35 & M4 X 0.8 X 15)
DPRF800		8.0" (200 mm)		5/16-24 X 1-3/4 & 8-32 X 1/2 (M8 X 1.25 X 40 & M4 X 0.8 X 15)
DPRF1000		10.0" (250 mm)		5/16-24 X 1-3/4 & 8-32 X 1/2 (M8 X 1.25 X 40 & M4 X 0.8 X 15)

                  When tightening the flange bolts, make sure the bolt heads and threads are in good condition, the threads are lubricated with anti-seize material and that the wrench fits properly. Turn the bolts deliberately and with great care. A stripped, seized or broken bolt can be frustrating. A slipped wrench can damage equipment or injure hands. Install the DPRF-series platform on your chamber/flange as you would any other ConFlat type flange. Use standard, 0.080" thick, flat copper gaskets. The following tightening sequence for lubricated bolts with washers is recommended. First finger tighten all bolts evenly, then sequentially torque the bolts in even steps.

For 4.5, 6, 8 and 10" Conflats Maximum torque 120-150 in/lbs.

For 2.75" Conflats - Maximum torque 80-100 in/lbs. For Mini Conflats - Maximum Torque 20-30 in/lbs.

Pumping:

                 The mini-conflat closest to the worm drive is marked "Inner". This means that this is connected to the innermost differential volume and the other mini conflat to the outer differential volume. If only single-stage differential pumping is being used, at least the inner one must be pumped, and it is probably a good idea to pump on both stages. NEVER ALLOW EITHER OF THE TWO PUMPING PORTS TO REMAIN UNCOVERED. The DPRF is sensitive to foreign matter entering the sealing system. The seal effectiveness and useful life are affected by the cleanliness of its environment. Particles can migrate through the pumping ports, contaminating the chambers, and this can cause seal failure. At all times, do one of the following:

1. connect the ports to suitable pumps.
2. cover the ports with the plastic caps provided (always remove during bake-out and replace with materials which will not melt).
3. cover with clean foil or other suitable material.

                 The ports are etched or stamped with the labels "INNER" and "OUTER". The markings are found on the mini-flange perimeters. Remove the protective caps to read these markings. The OUTER stage port is for the roughing pump, the INNER stage port is for the high vacuum pump.

Bakeout:

                  Bakeout in normal fashion, but NEVER exceed 100^oC with a motor or crank handle attached during bakeout. Higher temperatures can damage the components. If the motor or crank are removed, bakeout up to 150^oC. Monitor the temperature during bakeout. Never translate the platform during bakeout or when it is above ambient temperature.

Suggested pumping:

OUTER stage: >1.6 CFM at <10 microns.

                 Connect a roughing pump to the OUTER port flange. The roughing system must have a pumping speed of 1 CFM, or greater, measured at the port flange, and be capable of achieving a vacuum base pressure of at least 10 microns, measured at the DPRF pumping port flange. The platform should be protected from backstreaming oil or other contaminants with suitable traps.

INNER stage: ~2 l/s at ~10^-6 torr

                 Connect a high vacuum pump to the INNER port flange. The high vacuum system should have a pumping speed of ~2 l/s or greater, measured at the INNER flange, and be capable of achieving an operating pressure of at least 5 X 10^-6 Torr, measured at the DPRF pumping port flange. Higher pumping speeds and lower operating pressures will decrease the effective leak rates and decrease the pressure bursts upon rotation. Care must be taken to insure that significant pump speed losses due to conductance restrictions do not occur by using long lengths of small diameter tubing to connect suitable pumps. This is the most common cause of poor performance upon initial installation.

Using one stage pumping only:

                 If you wish to use only one pump stage, connect the pump to the INNER port. Cap off the OUTER port or plumb the OUTER port into the INNER port but DO NOT seal the OUTER port. Using one pump or no pump on the DPRF may cause the system base pressure to degrade and limit ultimate system base pressure but will not harm the DPRF.

Rotation:

                 The DPRF may be rotated continuously in either direction. The direction of rotation may be reversed at any time. Small pressure bursts may be observed near the DPRF as it is rotated. This is normal. This is due to the surface friction between stainless steel and the seal. Mass spectrometer studies show the bursts to be mostly water, methane, CO and CO₂ with small ammounts of H2. When pumping on both pumping ports, the typical pressure burst observed, with a system base pressure of 2 X 10^-10 Torr, will be 0.5 to 1.0 decade. Typical system base pressure recovery times range from 5 to 50 seconds, depending upon system condition and pumps used.

Maintenance:

                 Under normal conditions your DPRF will provide years of trouble-free service, especially if the following simple maintenance is performed. After several bakeouts, it may be necessary to relubricate the worm shaft and/or main bearing. Use the MoS₂ grease in the supplied syringe. The disk dial, worm gear and inner bearing retainer ring can be removed for bearing access. Note that the "O" ring seal above the bearing is to keep moisture and dirt out of the bearing. If your application is in a clean, moisture-free environment, this seal can be removed, thereby reducing torque required to rotate the platform. When replacing the screws in the disk dial, worm gear and inner bearing retainer ring, be sure to re-coat the threads with an anti-sieze compound.

                 Seal wear is not normally a problem when used as designed but high use or continuous operation will reduce service life of the seals. We recommend the DPRF be returned to the factory for service involving disassembly/assembly. The main reason for this policy is the sensitivity of DPRF units to contamination and mechanical damage of interior components and surfaces.

                 These units can be successfully serviced in the field if a clean work environment is available and adequate skill and care are used. The equipment warranty does not cover units which, in the sole judgement of McAllister Technical Services, may have been damaged during attempted customer repair.

Flexibility:

                  Since we are unable to predict the way in which each DPRF will be used, we have allowed some flexibility. On Models DPRF450 and larger, if the handwheel interferes with something on your vacuum chamber, you may remove it by removing the screw at its center and simply turn the hex end of the shaft with a ratchet wrench to actuate the rotary platform. Also, by reversing the shaft in the worm gear bracket, the handwheel can be placed on the opposite end. The entire worm gear bracket can be removed for easy bakeout or for rapid, non-precise rotation, by simply removing the socket head cap screws that hold the worm bracket on to the DPRF base. The worm gear bracket is self-aligning and takes only a moment to reinstall.

Packaging for storage or reshipment:

                  DPRF platforms are sensitive to contamination. As such, normal precautions in shipment are inadequate. If the need arises to re-ship the unit, or put the unit in storage, follow these guidelines:

1. Work on a clean surface when packaging.
2. Seal off both pumpout mini-ports with flange/gasket sets or snugly fitting plastic caps.
3. Protect and seal the flange surfaces. Use the original cover plates and clean foil, if possible.
4. Double bag unit in polyethylene bags. Seal each bag separately. Heat seal if possible. This is necessary to assure no packing material or foreign matter is able to contaminate the unit in transit.
5. 5) Re-use original carton with foam-in-place packing if available. If not, use suitable, non-migrating padding. Use adequate padding. Some shippers require 6" of padding be used for them to guarantee safe arrival of shipments. If the unit is being stored, or shipped to another user, include this manual in the package.

Accessories included:

1. Hex wrench kit
2. Spare screw kit
3. Gasket kit
4. Lubrication kit

Parts and factory service:

                  Replacement parts and non-warranty factory service are available on a fast turnaround basis. Please consult the factory with your specific need.