Recommended Separation Distances between Portable and Mobile RF Communications Equipment
The Expression MR400 MRI Patient Monitoring System is intended for use in an electromagnetic environment in
which radiated RF disturbances are controlled. The customer or the user of the Expression MR400 MRI Patient
Monitoring System can help prevent electromagnetic interference by maintaining a minimum distance between
portable and mobile RF communications equipment (transmitters) and the Expression MR400 MRI Patient Monitoring
System as recommended below, according to the maximum output power of the communications equipment.
Rated Maximum Output
Power Of Transmitter
For transmitters rated at a maximum output power not listed above, the recommended separation distance d in
meters (m) can be estimated using the equation applicable to the frequency of the transmitter, where P is the
maximum output power rating of the transmitter in watts (W) according to the transmitter manufacturer.
At 80 MHz and 800 MHz, the separation distance for the higher frequency range applies.
These guidelines may not apply in all situations. Electromagnetic propagation is affected by absorption and
reflection from structures, objects and people.
Using Batteries Safely
Batteries have life cycles. The battery life is at an end when the equipment operating time
provided by battery power becomes much shorter than usual (i.e., when the total battery
capacity has only 70 percent its initial capacity). For optimal battery life, please follow these
Immediately remove any battery that has an expired life cycle and replace it with a new battery
of the same type. (Refer to page 1‐37 for part numbers.) To ensure the safety of operators and
patients, observe the following warnings and cautions.
1‐12 Important Information Expression MR400 Instructions for Use
and the Expression MR400 MRI Patient Monitoring System
Separation Distance According To Frequency Of Transmitter (m)
150 KHz to 80 MHz
d = (3.5/V1)
Do not store the batteries in a discharged condition. Always charge a battery to at least 40
percent of capacity before storing.
Charge the batteries once a month when not in use.
80 MHz to 800 MHz
d = (3.5/E1)
800 MHz to 2.5 GHz
d = (7/E1)