UNISON OPEN SPRING MOUNT (OSM)
• Steel spring isolators are laterally stable even without any housing as they have the ratio of 1:1 approximately between the horizontal and vertical stiffness and as the free standing type complete with neoprene acoustical pads 0.25“(6mm) thick beneath the base plate this open spring isolators consist of top and bottom load plate and adjustment bolt for leveling which shall be rigidly bolted to the machineries.
• Spring should be designed to have the diameter not less than 80% of the one when it is compressed at rated load. Springs should also be designed to have a minimum additional 50% travel beyond rated deflection and safe solid stresses. For approval spring diameters, deflections, compressed spring height and solid spring height shall be submitted. We, UNISON Engineering Co., Ltd. manufactures the type OSM for this mountings.
• OSM spring mounts are for all installation of high efficiency for small force producing equipment related to air conditioning not requiring the use of snubbing to control movement, as our standard model. As an housed design, this assure lateral stability even without any housing because this has a good ratio between the diameter and the working height. Even though we have requested a minimum of 0.8 for the ratio of the spring diameter over the compressed height, we take a ratio of 1:1 for all of two inch deflection and far below two inch deflection.
• We consider that a minimum diameter chart pull shed by others rather than a ratio is prejudiced, because all other manufacturers who have not standardized on the specific size shall have difficulty on a predetermined diameter. Really important thing is the proportion of the spring which can be expressed as a ratio rather than a specific size. If, for instances, a spring diameter and height are 5“(125mm) respectively and designed spring constant is 1000lbs(450kgs) per 1”(25mm), it would have about the same lateral stability as a spring of 4“(100mm) diameter and height as it were possible to make it smaller design by using a material of higher stress capabilities.
• The errors which might be happened due to wrong weight data shall be compensated by minimum 50% of allowance. Also for further guarantees of its long life, the springs of this type operate at a low stress value, this type shall have the neoprene pad on the bottom to prevent transmission of very high frequency vibration and noise. OSM spring mounts provide simple, practical, cost effective solution for Vibration and Noise problems.
We, UNISON Engineering Co., Ltd. manufactures the various kinds of OSM spring mountings from 1“ deflection spring mountings to 4” deflection on spring mountin
After many years of our engineer‟s steady endeavor for the type OSM spring mountings, we designed these mountings to reduce noise and vibration and simplify installation and have established the following basic conditions. In putting together this spring mountings, we have used the springs which the ratio between spring diameter and operating height is excellent of equipments safety as well as equilibrium.
1. The ratio of the spring compressed height to the mean coil diameter hs/D and the radio of the static deflection to the compressed height st/hs.
For a good working order, the ratio hs/D suggested to be minimum 0.8. We apply bigger ratio than this in most of our design, Through the test of 1”, 2”, 3”, 4”, 5”(25, 50, 75, 100, 125mm) deflection series adhering above ratio as shown in the graph on the right, we were completely satisfied with this design.
2. The Elastic Limit
All of the springs shall be designed so as not to exceed the elastic limit when the coils are closed up and the springs are compressed solid. This prevents the springs damaged when they are overloaded, and assures a return to the spring‟s free height.
3. 50% Additional Travel to solid
In order to compensate weight distribution errors and to keep the springs operating in a low stress range, the rated loads and deflection shall allow for 50% additional travel to solid.
4. Neoprene Friction Pad and Leveling Bolts
A neoprene friction pad shall be placed one the bottom of the mountings to prevent the noise transmission, and spring loading and leveling bolts shall be provided at the top with locking cap screw. The leveling bolts are very important because they should be made rigid enough to maintain the alignment of the top of spring with the base plate.
5. Excessive Discharge Pressure
When the discharge pressure is excessive, this pressure can be reduced by adding mass using floating inertia bases, or in cases, adding horizontal thrust restraints.
6. Bolting Isolators to the Structure
Since it is expensive to bolt mountings down and any bolting procedure tends to bypass the acoustical action of the neoprene pad on the bottom of the mounting, we strongly recommend not to use these bolts except when earthquake codes or elevated installations on steel beams etc might be problem.
UNISON HOUSING TYPE SPRING MOUNT (HSM)
Type HSM spring isolators consist of high deflection, color coded stable springs assembled into plated, telescoping cast iron housings complete with 0.25”(6mm) thick neoprene friction pads beneath the housing and an adjusting and leveling bolt as a part of the top assembly. UNISON Engineering Co., Ltd. Manufactures type HSM for this mountings.
• Type HSM spring isolators provide an excellent solution to trouble and complicated vibration problems. These units perform when the establishing of low natural frequencies is required, and are specially designed for critical areas where the floors are light materials such as thin concrete, steel base or wood in order to free from noise and vibration.
• The limit of movement during start-up and shutdown and prevention of contact between the projections of the upper part and lower steel casting shall be performed by inserting the semi-circular sponge which are designed for a minimum damping in all directions to allow the springs to function adequately and achieve efficiencies as possible to theoretical efficiency. Inserts are recommended not adjustable for all air conditioning application with compressors, air handlers, centrifugal type fans, and most other vibration problems with constant frequency.
Type HSM spring mountings perform where it is required to establish low natural frequencies or to use a mounting whose yielding point is higher than that of the supporting floor because the static deflection of the spring element is much greater than that provided by most rubber materials, and are specially designed for noise and vibration free application in critical areas such as on light concrete or wooden floors.
1. Neoprene Sponge Inserts
• It is required to limit the movement during start and stop of the mountings and to prevent any contact, and for this purpose, semi-circular neoprene sponge shall be inserted into the gap between the projections of the super and lower semi-steel castings. A minimum of damping in all directions shall be considered in the design in order to allow the springs to function properly and develop installed efficiencies as close as possible to the theoretical efficiency.
• These inserts shall be recommended not to be adjustable for all air conditioning applications such as compressors, air handling units, centrifugal fans and most other equipment which produce constant frequency vibration.
In order to avoid the direct friction between ground concrete and HSM spring mounting housing, acoustical friction pad is attached on the bottom of housings.
2. External Adjustment Mountings
For the equipment whose mounting holes are well centered and mounting leveling and adjustment bolt is easily accessible from above external adjustment mountings shall be installed.
3. Internal Adjustment Mountings
The equipment which is preferable to change the center of the mounting according to its mounting hole or has no access for adjustment from above, internal adjustment mountings shall be provided, An open end wrench will work successfully for adjustment of internal spring through the side opening. Type W. acoustical friction pads on the bottom of the mountings for both external and internal shall eliminated the need for bolting down on most installations.
UNISON RESTRAINED SPRING MOUNTS (RSM)
For the equipment with weight variations between operating and installed weight such as boilers, refrigeration machines etc, and outdoor equipment such as cooling towers exposed to wind load, spring isolators can be used but for the prevention of spring extension due to weight removal, a housing having vertical limit stops shall be provided. The housing shall act as blocking during installation. A minimum 0.5”(12mm) clearance around restrain bolts and between the housing and the spring shall be maintained for not interfering the spring movement. During normal operation the limit stops shall be free from contact,. Hot dipped galvanized unit shall be supplied for outdoor installation UNISON Engineering Co., Ltd. Manufactures the type RSM for the mountings.
Type RSM restrained spring isolators have hold-down bolts to limit vertical(upward) movement when loaded weight is temporarily removed and provide safety stops when lateral movement might be happened due to windy roof top installation. The rigid sides act as non-yielding blocks and support the equipment at elevation before spring adjustment which can be accomplished by inserting shims between the top plate and the flat shims are removed after spring Adjustment so maintain operating gap without changing the mounting height.
RSM spring mountings are covered with hot dipped galvanized paint for oxidization prevention in outdoor installation. RSM spring mountings are specially designed to withstand high levels of Vibration and shock and to protect equipment from impact shock, The role of RSM spring mountings. Is to serve as blocking during erection and to prevent spring extension when weight is removed. RSM spring mounting are particularly suitable for heavy stamping machines such as cooling tower.