Mks Instruments, Inc.

Frederick J Luft

Paul D Lucas

Ting Huang

The disclosed mass flowmeter includes a section defining a passageway and a laminar flow element disposed within the passageway so as to define a laminar flow channel within the passageway. The maximum cross sectional dimension of the laminar flow element is smaller than the maximum cross sectional dimension of the passageway. In one embodiment the flowmeter includes a device for mounting the laminar flow element within the passageway so that the laminar flow element contacts at least a portion of an inner surface of the passageway so that various sized laminar flow elements can easily and reliably be substituted for one another so as to select the mass flow rate through the channel. In a second embodiment the laminar flow element includes two support segments which are fitted within the passageway and support a central segment which defines within the passageway the laminar flow channel. In the latter embodiment the support segments can be fixed within the passageway in various ways, including providing the support segments as end segments and forming end slots in the end support segments so that wedging pieces, in the form of balls or pins, for example, can be inserted so as to spread the slotted portion of each end segment apart so as to hold the laminar flow element firmly in place. In another embodiment the position of at least a portion of the laminar flow element is adjustable between one of two positions so that the cross sectional shape of the channel can be modified so as to modify the flow rate through the channel.

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Nashua, NH, United States of America

Frederick J Luft