MRI machines, so useful in diagnosing medical conditions, rely on extremely strong magnetic fields to produce highly detailed images of tissues inside the human body. The coils that produce these magnetic fields are many feet in diameter. The fields are so strong that if a piece of equipment located near the MRI machine is made of a magnetic material (such as steel, which is attracted by magnets), that equipment would be quickly pulled against the MRI machine – perhaps with disastrous consequences!
The challenge for designers of equipment that must be operated near the strong magnetic fields of MRI machines is to find components that are non-magnetic. For mobile equipment like medical carts or seating, almost all available casters are made with at least some parts that are magnetic. Steel axles, for example, are commonly used in casters – but must not be used anywhere close to an MRI machine.
Designers who succeed in making casters that are sufficiently non-magnetic can obtain the status of MRI Conditional for their products. This means the casters can be safely used near MRI machines. Douglas Equipment carries MRI Conditional Casters; we will describe two of our models below.
Shepherd’s MRI Conditional Casters – the SofTech MRI Series
Shepherd Caster is a very interesting company – they keep on innovating! Ever since their beginnings in the 1940s and 1950s, when they invented unique casters for use on furniture in the home and residential markets, they have continued to develop original products for new markets.
The company was founded in the mid-1950s to manufacture their first product, Planet Ball Casters. These casters, aimed at the residential market, made it easy to move chairs or furniture over carpeted floors. A decade later, Shepherd created their innovative Twin Wheel casters for the office seating market. Shepherd later refined their Twin Wheel casters and developed the SofTech Series, which uses a high-tech thermoplastic elastomer tread, giving a cushioned ride and quiet mobility not usually found in a twin wheel caster.
Why the Need for Non-Magnetic Casters?
When MRI machines became available, creating the need for special non-magnetic casters, Shepherd continued to innovate. They modified their SofTech Series, and created the SofTech MRI Series, which was developed specifically to perform well in the demanding conditions that exist near MRI machines.
These casters are rated MRI Conditional. To clearly show to staff in a medical facility that the casters are approved for use around MRI machines, the center of each wheel has an easily recognized universal logo. Shepherd’s MRI Conditional Casters are ideal for use on equipment such as rolling carts, office seating or any medical equipment operated around or near MRI machines.
How MRI Conditional Casters are Designed
Shepherd obtained MRI Conditional status for their SofTech MRI Series by using a component design that features all non-magnetic stainless steel. Shepherd specifies materials for these casters that will not be attracted by magnetic fields and then manufactures the casters in an extremely controlled process to ensure their non-magnetic status.
Available wheel diameters for the SofTech MRI Series are 50 mm, rated for dynamic loads of 75 lbs; 60 mm, rated for dynamic loads of 100 lbs; and 75 mm, which are rated for dynamic loads of 165 lbs. Mounting options include threaded stems and grip stems. For positive wheel retention, the casters are made with riveted axles.
The wheel tread is made of a soft 70-75/A durometer thermoplastic elastomer, which provides quiet mobility to any equipment mounted on these casters. The wheels are non-marking, and provide good floor protection.
SofTech MRI Series casters are available in gray or black. Brakes are available for all of the models.
The SofTech MRI Series is also a good choice in applications where water and moisture can present corrosive conditions. These casters resist corrosion very well, thanks to their stainless steel components and construction details mentioned above.
MedCaster’s MRI Conditional Casters – Non-Magnetic Nylon (NM)
Douglas Equipment is an authorized distributor for MedCaster, a company which provides another option for MRI Conditional Casters.
MedCaster uses nylon and 316S stainless steel in the construction of their Non-Magnetic Nylon (NM) casters. These materials allow the casters to have reduced magnetism, making them ideal in applications where casters must be used near strong magnetic fields, such as those produced by MRI machines.
NM casters have ball bearing raceways made from 316S stainless steel. The raceways are precision sealed, making them maintenance free. Delrin bearings used in the wheels gives the casters a quiet and smooth ride.
For mounting the casters, you can choose between top plate models or threaded stem models. The casters are available with Total Lock Brakes that lock both the wheel and the swivel. Directional lock brakes are also available that lock the swivel only, and help with steering.
Three-wheel diameters are available: 3” wheels with capacities of 100 lbs; 4” wheels with 150 lbs. capacities; and 5” wheels, which are rated for 200 lbs. The wheel tread material is QuikStart TPR Thermoplastic Rubber, which contributes to the smooth ride of these casters. The plastic cover over the recessed axles is colored green, to indicate the non-magnetic properties of NM casters.
All the properties listed above make MedCaster’s NM Casters ideal for use on MRI conditional equipment. Because the casters are maintenance-free and resistant to most chemicals, they are also great for use on hospital and utility carts, medical equipment, and electronic equipment.
For the Best in MRI Conditional Casters – Contact Douglas Equipment!
When you are faced with a unique requirement for your casters, it can be difficult to find the one model that might meet your needs. And that’s where Douglas equipment comes in! The experts in our customer service department can quickly help you find exactly what you need – even something as unique as MRI Conditional Casters, which must be non-magnetic and function well, even in extremely strong magnetic fields. You can reach our customer service team at 800-451-0030, or 305-888-3700 in the Miami area. You can even ask us a question online through our contact form today!