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Parking and Access Requirements
The mobile MRI trailer unit weighs up to 30 tonnes. The trailers
are approximately 14 metres long and 2.6 metres wide.
Access consideration must be given to the tractor, the patient
lift, the stairs and the belly compartments, for patient entry,
trailer service and helium dewar access to fill the magnet. A total
paved area of at least 6 x 20 meters is recommended for tractor
access and patient handling.
It is important that the site is level. It is possible to accommodate
a fall of no more than 150 mm over the length and 50 mm over the
width of the unit. Road quality surface for the site is acceptable
provided that there are no drains, ducts or other below ground structures
that could be damaged by the weight of the scanner.
When parked, the unit uses two front hydraulic jacks and two fixed
height stands in the rear, for stabilising purposes or four fixed
height stands if a full size pad is available. The trailer is placed
on ‘spreader plates’ that spread the load to avoid damage
to the road surface.
In cases where the ground cannot support the scanner in the proposed location, a concrete support pad constructed to
ensure a level surface capable of accommodating the weight of a mobile scanning unit is recommended.
Pad Requirements
The following is a list of recommendations and requirements for
a concrete support pad however, due to varying site conditions a
local contractor should be consulted for actual pad design.
Support Pad
A full pad measuring 3.04m x 13.68m located as shown on the diagram
below. The support pad must be level (no more than 150 mm variations
over length and 50 mm variation across length) to insure proper
operation of the Mobile MRI System.
Service Pad
A full pad measuring 6.40m x 15.50m located as shown on the diagram below, is recommended to provide service access. This
is optional if space is available.
Steel Reinforced Concrete Pad
Maximum 20kg/m2 of steel.
Power Requirements
Mains Electrical Supply
A single electrical power source is required for operation of the MRI system.
3/N/PE AC 400V service fused at 175A per phase.
Configuration
Three phase, five wire, wye connection, with neutral and ground.
(5 wire 3/N/PE AC 400V)
Load Regulation at Line Frequency
Wires are to be sized such that the line voltage drops from the
power source to the mobile unit is less then 2% of the nominal voltage
for the rated load of the mobile unit.
Frequency
50 Hz + 0.5 Hz.
Phase balance: 2% maximum of lowest phase-to-phase voltage.
Maximum Voltage Variation: + 5% from a nominal steady state (under
the worst case conditions of line voltage).
Connector type
The mobile unit is supplied with a 35'-0" (10.668m) useable
power cable and male conductor. AMIS scanners come equipped with
both Marechal DS2 and Lewden PM125/808 type male connectors. The
Lewden connector is a version of the CeeForm CEE 17 125A 400V (red)
connector.
Customer Facility
The customer facility must have the matching receptacle. Unless
otherwise specified, the receptacle type to be used must be either
a Marechal DS2 or the CEE17 125A female connectors.
Mobile Grounding Requirements
Ground Wire
An insulated ground conductor sized in accordance must be installed
between the facility vault and the mobile system ground bus location
in the power distribution unit.
Special Ground Note
The mobile unit includes an earth driven ground rod within 5’-0” (1.524m) of the facility power receptacle.
A grounding cable of a minimum #1/0 AWG must be connected between the grounding rod and the grounding pin of the facility
power receptacle, and another cable to be kept as short as possible, and must not exceed 8’-0” (2.4384m) in
length. A separate grounding conductor must still be run with the phase conductors to the source of the power from the
grounding pin of the hospital power receptacle.
Additional Requirements
Magnetic shielding
Due to the fact that the trailer is executed with magnetic shielding,
the 5-gauss line remains within the width of the trailer. Therefore
additional safety-provisions outside the trailer are NOT necessary.
Nevertheless heavy steel constructions may influence the optimal
image quality. If a patient walkway is constructed from a building
to the trailer it is therefore recommended that it be of non-ferrous
material. No connection to trailer wall is to be attempted.
RF shielding
The RF shield is included with the MR system and will provide minimum
level of attenuation: 10 MHZ – 100 MHZ 85 dB (plane wave,
electric field, magnetic wave).
Water requirements
The trailer has a humidification system, which contains a water
storage tank, located in the front technical compartment. This tank
must always contain water to ensure a specific humidity level.
Telephone service
Two telephone lines are required for the operation of the mobile unit: a normal telephone line to enable the scanner to
communicate with the hospital, and (optional) a dedicated direct line of modem connection. In the trailer belly compartment,
there is a Hubbell phone connection socket. An adaptor must be provided to connect from the local phone socket to the
Hubbell.
Site Checklist
This checklist is provided to help you prepare your site for the mobile unit. If for any reason you cannot meet these
points contact AMIS for possible alternatives.
- Trailer access route determined.
- Trailer exit route determined.
- Tractor access checked.
- Service access clear around trailer.
- Vibration/moving metal restrictions.
- Support pad.
- Communication lines.
- Electrical service checked and meets specs.
- Grounding checked.
- Mains impedance checked.
Mobile MRI Drawings
Download a complete Mobile
MRI Unit site planning guide. - 4 minute download.
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