Frequently Asked Questions

If you have questions, we always advise you to first check our FAQ section. If you are unable to find an answer or need additional information, please contact us.

Fluid Rotary UnionsBack to Top

What is a rotary union?

A rotary union (or swivel joint) is a device used to transfer fluid under pressure or vacuum from a stationary inlet to a rotating outlet, preserving and isolating the fluid connection. Learn more about What is a Rotary Union?

How do I choose a rotary union?

Proper selection of a rotary union solution requires details about your application's operating parameters including pressure, speed, media type(s), number of flow passages (channels), and connection size(s) / type(s). A good place to start your search is with our Fluid Rotary Unions. If you are confident that a custom / modified solution is most likely required or need assistance in your selection, contact us to Get Started. Our experts are here for you.

Do you offer custom rotary unions?

Yes, it's what we do best! We can meet your exact fluid rotary union requirements from modifying our standard products to complete, custom design and manufacturing. For more information see Custom Solutions

What is your process for a custom rotary union solution?

First, contact us to Get Started. Our team will reach out to you to start learning more about your project's technical and delivery requirements. We will consider all aspects of your application and work together to develop the best solution. We typically start by evaluating our in-stock standard product options, reviewing our extensive library of custom rotary union designs, and examining a complete custom solution.

We will present a detailed proposal including proposed design, cost breakdown, and project timeline. You will be assigned a sales engineer and project manager so you know who to go to with any questions throughout the process. For more information see Custom Solutions

Do you offer compatible options for replacing another manufacturer's fluid rotary union?

Yes, we can cross reference other manufacturer's fluid rotary unions to find an equivalent solution. Contact us to Get Started

Can your standard rotary unions be modified to meet the requirements of my application?

We can modify our standard rotary unions to fit your needs. Custom modifications to our standard products are quite common and easier than you may think. Modifications include changes to housing / shaft dimensions and materials, seal types, mounting configurations, connection sizes and types, and flow passage configurations. For more information see Standard Rotary Union Modifications

Do you offer replacement seals and/or bearings for rebuilding your rotary unions?

Yes, seal and bearing kits are available for our rotary union products for on-location rebuilding and repair. Contact us to Get Started

Do you offer fluid rotary union / electrical slip ring combination assemblies?

Yes, DSTI fluid rotary union and electrical slip ring technology can be integrated together into one complete solution for fluid, power, signal, and data transfer. We offer both standard (in-stock) assemblies and custom solutions designed to meet your exact requirements. For more information see Fluid + Electrical Solutions.

Can I use a different media than what is listed on your site?

DSTI products are only recommended for use with the specific media types listed. This ensures proper compatibility with all components; shaft / housing, bearings and seals.

How do I install/mount my rotary union into my equipment?

CAUTION: DSTI does not recommend mounting the rotary union with both the shaft & housing components solidly bolted into place. One of the two components should be mounted in a manner that allows for some movement in the event of misalignment. Using only the supply lines or hoses to fix the stationary component in place is also not recommended. An anti-rotation arm that attaches to the stationary part of the rotating union assembly and rests against part of the equipment framework is recommended.

Shaft mounted units with O-ring face seal glands (-OF option in product code):

1) Make sure the rotating union shaft face & equipment mounting surface is clean and free from dents or chips to insure proper installation. Equipment pilot bore needs to be concentric to the center line of the rotating union shaft to assure proper function.
2) Install face mount O-rings into seal gland on shaft face. General assembly grease can be used as needed to hold O-rings into place during assembly.
3) Align rotating union shaft with equipment pilot bore and flow passages, then insert into place.
4) Bolt assembly into place using tapped holes or optional mounting flange (see below) on rotating union face.

Shaft mounted units with threaded connections:

1) Make sure all fittings are properly tightened & pipe thread tape is used as required. Equipment mounting surface needs to be concentric to the center line of the rotating union shaft to assure proper function.
2) After all fittings are in place, bolt assembly into place using tapped holes or optional mounting flange (see below) on rotating union shaft.

Optional Mounting Flanges: DSTI shaft and housing mounting flanges are available for purchase. To order, contact a member of our Sales Support Team.

Customer Interface Adapters: DSTI does not manufacture customer interface adapters for stock products. If ordering a custom rotary union, DSTI can design the union to integrate directly into your equipment.

What do the letters R.A in the Product Code mean?

The letters R.A are an abbreviation for Revision A. This gives DSTI the ability to manage revision control on all products.

Can I use more than one media type in a rotary union at the same time?

Yes, if all media types are suitable for that specific rotary union. However, if using air/gas and another fluid, DSTI recommends using a rotary union with an extra passage (empty) between the two to avoid cross contamination. Please speak with a member of our Sales Support Team to discuss your application in detail.

Can I run air and fluid in the same rotary union?

DSTI recommends using a rotary union with an extra passage (empty) between the two to avoid cross contamination. Please speak with a member of our Sales Support Team to discuss your application in detail.

What causes a rotary union to fail?

Common causes of early failure are dirty, unfiltered media, vibration, exceeding operating parameters, excessive heat, improper installation, etc.

Can a rotary union be rebuilt?

Yes. All standard DSTI rotary unions can be rebuilt assuming no damage to sealing surfaces have occurred. There are two options for rebuilding:

1) Purchase a do-it-yourself service kit that includes either seals (only) or seals and bearings. Contact a member of our Sales Support Team for pricing and availability.

2) Send the unit to DSTI for repair evaluation. A Return Merchandize Authorization (RMA) number is required prior to returning any DSTI products. Request a RMA Number.

What is a through bore?

A through bore is a hollow, center-bore that provides routing space for passing electrical wires or other components through the middle of the rotary union. It can also be used to mount the rotary union to a custom interface.

What is the life expectancy of a rotary union?

The life expectancy of a rotary union varies widely depending on many application variables: media type, pressure, rotational speed, duty cycle, temperature, and more. If you need further assistance contact a member of our Sales Support Team.

Is there a quantity price break if I order multiple units?

To discuss quantity price breaks, contact a member of our Sales Support Team.

How much torque is require to rotate a rotary union?

Each product lists the minimum torque needed to rotate the rotary union at zero pressure under the Additional Information tab.

Can I rotate the rotary union dry (no media flowing)?

Yes. Although there may be some adverse effects if it is run dry for a prolonged period of time under extreme conditions, for example, high rotational speeds and/or elevated temperatures. Contact a member of our Sales Support Team to discuss this topic more in detail.

What do the letters -OF in the Product Code mean?

The letters -OF in the product code is for an optional "O-ring Face Seal Gland" for flush mounting the rotary union to the customer’s interface. When this option is ordered the side connections on the shaft are plugged (if applicable).

Can an axial and/or radial load be placed on a rotary union?

In most cases, some degree of load can be placed on a rotary union, but please contact a member of our Sales Support Team to better understand your application needs.

Which part of the rotary union stays stationary and which part rotates?

Functionally it makes no difference whether the shaft or the housing rotates. It is all dependent on how the assembly is mounted and installed on your machine or equipment.

Electrical Slip RingsBack to Top

What is a slip ring?

An electrical slip ring is a device used to transfer power and data from a stationary to a rotating structure. Slip rings can provide continuous or intermittent rotation while transmitting power and data - simplifying operation, improving application performance, and eliminating risk of damage to wiring between movable parts. See Electrical Slip Rings

How do I choose a slip ring?

Proper selection of a slip ring solution requires details about your application's operating parameters including total circuits, voltage and amps per circuit, operating speed, and mounting type. A good place to start your search is with our Electrical Slip Rings. If you are confident that a custom / modified solution is most likely required or need assistance in your selection, contact us to Get Started. Our experts are here for you.

Do you offer electrical slip ring / fluid rotary union combination assemblies?

Yes, DSTI fluid rotary union and electrical slip ring technology can be integrated together into one complete solution for fluid, power, signal, and data transfer. We offer both standard (in-stock) assemblies and custom solutions designed to meet your exact requirements. For more information see Fluid + Electrical Solutions

Do you offer custom slip rings?

Yes, we work directly with our slip ring partners to design custom solutions to meet your exact electrical requirements. For more information please see Custom Slip Rings

Why are your slip rings so expensive? I can find other slip rings online for far less.

DSTI slip rings are some of the best in the industry. They utilize a maintenance-free, low-torque design with gold-on-gold contact technology for low electrical noise and un-parallel performance.

How do I install/mount my slip ring into my equipment?

CAUTION: Because of possible geometric mismatching between the customer’s application and the slip ring, “hard mounting” of both ends of the slip ring (i.e., securing the rotor and stator such that there is NO floating during operation) is not recommended and may cause premature failure.

To mount capsule slip rings:

1) The slip ring capsule is designed to be flange-mounted with the barrel cantilevered.
2) The rotor must be driven with a flexible coupling (i.e. rubber tubing, helical or bellows-type) to accommodate any eccentricities in the mounting. The rotor leads can be used as a flexible coupling for operation at speeds up to 5 RPM.
3) Use (3) screws with flat washers to mount the slip ring. If lock washers are also used, flat washers should be mounted between the lock washers and the flange. (Hardware not included)
4) The slip ring is not designed to bear the weight of the equipment to which it is connected. Rotating equipment should be secured so that no axial or radial load is applied to the slip ring rotor.
5) The slip ring should be protected from dust and moisture. For outdoor installations, the slip ring should be installed in a weatherproof enclosure.
6) Secure all leads so that they do not rub against any surface as the equipment rotates. Care should be taken when routing and securing the leads so that no side loading of the slip ring occurs.

To mount through bore slip rings:

SHAFT MOUNTED UNITS

1) Position the slip ring in the desired location and equally tighten both set screws to the shaft on each end of the union. Torque to 25 lb-in.
2) Route the wiring and make the necessary connections. Do not allow the wiring to restrict free rotation of the slip ring.
3) Position a screw or dowel (not supplied) in the anti-rotation tab.

FLANGE MOUNTED UNITS

1) Align the mounting holes in the flange to mounting base and install flat washers and thread forming screws (NOT SUPPLIED) for plastic. Securely tighten screws.
2) Route the wiring and make the necessary connections. Do not allow the wiring to restrict free rotation of the slip ring.
3) Position a screw or dowel (not supplied) in the anti-rotation tab.

Is there a quantity price break if I order multiple units?

To discuss quantity price breaks, contact a member of our Sales Support Team.

Can I combine multiple circuits to get higher current/amps?

In some cases it is possible. Please contact a member of our Sales Support Team to better understand your application needs.

Are DSTI slip rings waterproof?

DSTI standard slip rings are not waterproof, however they are IP51 rated, meaning they offer limited dust and condensation protection. If your application requires a waterproof slip ring, contact a member of our Sales Support Team to discuss custom slip ring options.

Are DSTI slip rings explosion proof?

No. DSTI standard slip rings are not explosion proof. If your application requires an explosion proof slip ring, contact a member of our Sales Support Team to discuss custom slip ring options.

Can I run EtherCAT/Profibus/Profinet/USB/Cat5/Cat6 with DSTI slip rings?

There are almost endless options for transferring power/data with electrical slip rings. Contact a member of our Sales Support Team to discuss your electrical needs. If an option is not available with one of our standard product offerings, we can develop a custom solution to meet slip ring configuration needs.

What connection type do the Ethernet cables use in your Ethernet slip rings?

All Ethernet cables are terminated with Registered Jack 45 (RJ45) connectors using T568B wiring standards.

Do you offer different lead lengths?

Some of our slip rings can be custom ordered with longer lead lengths. Contact a member of our Sales Support Team to discuss your application needs.

What is the gauge of the wiring?

Wire gauge varies by product and current. Generally, all 2 amps are 26-28 AWG, 5 amps are 20 AWG, and 10 amps are 16 AWG. For specific wire gauges, download our Slip Ring & Wire Color Code brochure.

What if my voltage rating is slightly higher than your recommended voltage?

There is a small degree of padding built into the listed maximum voltage ratings. Contact a member of our Sales Support Team to discuss your application needs.

Are DSTI slip rings UL rated?

No. DSTI standard slip rings are not UL rated.

What frequency (Hz) are the slip rings rated for?

DSTI standard slip rings are rated for 0 - 150 mHz. If your requirements fall outside that range, contact a member of our Sales Support Team to discuss other options.

Are DSTI slip rings certified to military standard/MIL-STD/MIL-SPEC?

No. DSTI standard slip rings are Commercial - Industrial Grade.

Can DSTI slip rings work with RF signals?

No. RF signals are much more complex than DSTI standard slip rings can handle.

What temperature are the leads rated for?

The slip ring assembly is rated to 176°F [80°C]. The leads are rated to 221°F [105°C].

Orders & ShippingBack to Top

Do you accept credit card for payment?

Yes, we accept American Express, Visa, and MasterCard.

Can I expedite my order?

Yes. In most cases, if the product is in-stock. Please contact a member of our Sales Support Team to discuss delivery options.

Is there a quantity price break if I order multiple units?

To discuss quantity price breaks, contact a member of our Sales Support Team.

Can I ship to International/APO/FPO addresses?

Currently, the DSTI Store (store.dsti.com) only ships to customers within the United States. For orders requiring international shipping, contact a member of our Sales Support Team to get started.

Can I ship my order to someone else?

Yes. Orders can be shipped to a different address than your billing address. During checkout you will have the option of entering a shipping address seperate from the billing addresss

Can I arrange my own shipping or provide an account number (UPS/Fedex)?

Currently, the DSTI Store (store.dsti.com) does not allow customer arranged shipping or use of an account number (UPS/Fedex). If this is required, please contact a member of our Sales Support Team to discuss your shipping needs.

How do I know when my order ships?

When your order ships, you will receive an email confirmation with the tracking number(s) and estimated delivery date(s).

What do the different Availability options mean?

In-Stock, available to ship in 1-2 business days: Item is in-stock and ready to ship.

In-Stock, available to ship in 5-7 business days: Item is in-stock but will need to be assembled and tested before it’s ready for shipping.

Limited Availability: One or more of the components are currently not in-stock. Please fill out the "Get Quote" form located on the product page you are interested in and a member of our sales support staff will contact you.

What shipping methods are available?

All items are shipped from Andover, Minnesota FOB Origin via UPS Ground, 3 Day Select or Next Day Air.

How do I track my order?

When an order status is updated, we will update your order dashboard within your DSTI Store account (if applicable) and email the status update to your email address provided on the order. When an order ships, we will email the tracking number(s) for you to follow the path of your order from our warehouse to your destination.

Warranty & ReturnsBack to Top

Where can I find your product warranty information?

For warranty information please see Product Warranty

What is your return policy?

New, unused rotary unions purchased from the DSTI Store (store.dsti.com) are returnable within 90 days and are subject to a 20% restocking fee.

Electrical slip rings are non-returnable.

A Return Merchandise Authorization (RMA) number is required prior to returning DSTI products. For more information see Return Policy

How do I return a product for refund or credit?

A Return Merchandise Authorization (RMA) number is required prior to returning any DSTI product for refund or credit. A RMA number will be created upon completion of the RMA Form and member of our sales support staff will contact you with further instructions.

How do I return a product for warranty evaluation or repair?

A Return Merchandise Authorization (RMA) number is required prior to returning any DSTI products for warranty evaluation or repair. For more information see Return Policy.