**Magnet/Syringe Separation Issues**

**V.B. Graves**

**8/12/05**

This document is an initial response to the results of Peter\'s analysis
on the attractive forces between the magnet and the steel hydraulic
cylinders in the baseline syringe pump design.

Based on the conversations I have had with hydraulic integrators,
aluminum cylinders are not practical at the intended operating pressures
and are not an option for the Hg cylinder in any case. It appears the
only solutions to this problem are to either use all-stainless cylinders
or separate the cylinders from the magnet. Since the cost of stainless
cylinders is prohibitively high, the practical solution is to increase
the distance between the magnet and the cylinders. While Peter\'s
analysis indicated that 1m would be a sufficient separation distance, in
our subsequent phone conversation we thought that a separation distance
of 2m might be preferred as a conservative approach to the analysis
results, and my comments below reflect that value. The final value is
TBD.

To minimize changes to the current design (Fig. 1) this separation would
most easily be accomplished by increasing the length of the flexible
hoses between the sump tank and the target module, keeping the sump tank
and cylinders inside a secondary container box. The secondary bellows
surrounding the Hg supply and return lines would necessarily lengthen as
required. Conceptually this is shown in Fig. 2. This change has several
implications on the design, some positive in nature and some negative. I
have listed some of these below, but I\'m sure that more will develop as
the redesign progresses. *Those issues that deal with the cylinders must
be resolved prior to the syringe pump procurement.*

![](media/image1.jpeg){width="5.364583333333333in" height="3.125in"}

Fig. 1. Existing Design

![](media/image2.jpeg){width="5.997222222222222in"
height="2.203472222222222in"}

Fig 2. Separated System (use your imagination to insert the target
module into the magnet). Magnet elevated to beam height, syringe system
on floor. Intermediate hose supports not shown.

# Baseplate

-   The common baseplate cannot be extended 2m in length due to the
    fixed beam elevation and facility constraints both at MIT and CERN.
    This implies that a common baseplate is not needed. However, it is
    still required that the magnet be elevated, tilted, and aligned with
    the beam, so some sort of magnet baseplate will be necessary.
    Because it already incorporates a means to perform alignment
    adjustments, one option would be to shorten the current baseplate so
    that it only supports the magnet.

-   With flexible hoses, the syringe does not have to be tilted and may
    sit directly on the floor (or a mobile baseplate).

-   The syringe system no longer has to be directly in line with the
    magnet or beam, which would allow some flexibility in positioning.
    This may be beneficial during integrated tests at MIT.

-   With 2m of flex hose, the target module might be manually inserted
    into magnet, so syringe system does not require rolling cart.
    Estimated weight of the target module is 100-150 lbs.

# Cylinders

-   With no magnetic attraction forces to deal with, carbon steel
    cylinders, rods, and pistons can be used in the drive cylinders. The
    Hg cylinder will still be designed for water service (i.e., chrome
    plating cylinder walls, piston, rod)

-   Because the syringe is no longer interfaced to the magnet through
    the common baseplate, minimizing the syringe length is no longer a
    driving requirement. The Hg cylinder diameter could decrease from
    10\" to 8\", putting it in the \"low-cost\" family of cylinders.
    With an 8\" Hg cylinder, maintaining the 12-sec jet requirement will
    increase the required stroke by 8\" and the total extended length by
    approximately 13\".

# Extended Hoses

-   Added flex hose will require support to prevent sag due to Hg
    weight.

-   Flexible hoses have internal convolutions that will trap Hg in these
    slightly-sloped hoses and will have more flow resistance than rigid
    pipe. For flow reasons, it would be preferable to use rigid pipe for
    most of the new length with flex hoses on one or both ends. Use of
    2m of rigid pipe makes it impractical to ship and transport
    assembled system (syringe, pipe, target module), so assembly and
    disassembly of the primary containment would be required at MIT and
    CERN. However, the use of rigid pipe is not absolutely required, and
    the desire to not open the primary containment in the MIT and CERN
    facilities probably overrides the flow issues.

-   Pressure drop across 2m of new pipe will be calculated; increasing
    pipe diameter reduces pressure drop but would require additional Hg
    inventory.

-   Additional length of pipe requires additional Hg inventory to
    pre-fill supply line prior to syringe actuation (2m of 1\" pipe will
    require approx 1 additional liter). Some slightly increased amount
    of cylinder stroke will be lost to pre-filling the additional
    volume.

-   The 6\" diameter Hg return hose is fairly expensive (\$2100 for
    18.25 inches), so adding another 1.5m is not an insignificant
    expense. I will probably go with a smaller diameter hose for the
    return line.

-   Since they interface through the secondary containment box,
    hydraulic lines, sensor wires, ?scintillator?, and optic fiber
    bundles will have to be longer since they will be further from the
    TT2/TT2A junction. The fiber bundles and scintillator cables will be
    inside the flexible secondary containment along with the Hg supply
    and return lines.

# Target Module

-   Because the syringe pump & containment box would be positioned below
    the beam, the downstream secondary beam window would move to the
    target module rather than the secondary containment box.

-   Downstream end of target module would require changes to accommodate
    different secondary containment.

-   Supporting the target module off of the secondary containment box
    from 2m away is not practical (see Fig. 3). Secondary containment
    baseplate could have provisions for storage of target module.

![](media/image3.jpeg){width="5.9944444444444445in"
height="2.1756944444444444in"}

Fig. 3. Existing target module bracing method