ri,. iv. \- PRECISION BALANCE MODEL (CAPACITY 101g Directions for Use and Maintenance

Transcription

1 @en PRECISION BALANCE Directions for Use and Maintenance Please read this manual before unpacking, assembling and using your balance. MODEL (CAPACITY 101g X.01g) ri,. iv. \- I\:J Ohaus Scale Corporation 1983 all rights reserved

2 IMPORTANT! In order to gain an understanding of the use of the two poise system, it is recommended that you take a few minutes to read these instructions before you attempt to use your balance. UNPACKING AND SETUP Remove the balance from the carton and discard the outer pl astic wrapper. Turn the bal ance upside down. Using a wrench or pliers, loosen the large acorn nut at the left end. This will free the leveling foot. Pl ace the bal ance on a reasonably fl at and level surface. To remove the cover, apply thumb center pressure of the at the cover depression and li ft in off. the front Note that your bal ance is designed to sel f- store all its parts. As you remove parts, notice how they store tions. so you can return them to these posi CAUTION! The end loop MUST not be bent or twisted when unpacking. For your scale to operate properly: Both sides of the end loop MUST be parallel to the beam. The end loop shall move freely in the pivot notches and hang in a position perpendicular to the knife edges. Remove the pan support and pan and set to one side. Remove the beam from its storage position ar.d discard the inner pl astic wrapper. Insert the beam in its bearings, making sure to position the copper damper vane in the slot at the left end of the base. Hang the pan support and pan from the end loop. Note the way the pan support cradl es the pan. This feature makes it possible to weigh long, heavy obj ects wi thout ti ppi ng the pan off its support. The pan support may al so be rotated within the wire hanger for a more convenient h and 1 e po sit ion. Your bal ance is now ready for use.

3 HOW TO ZERO BALANCE Pl ace both the large poise and the micrometer poise at zero. If the balance has been placed on a reasonably level surface, the beam pointer will come to rest fairly close to the zero graduation on the dial pl ate. Raise or lower the left end of the base by means of the 1 evel ing foot to line them up. THE BALANCE SHOULD BE ZEROED BEFORE USE AND CHECKED PERIODICALL Y DURING USE FOR MAXIMUM ACCURACY AND PROTECTION AGAINST ERROR. MAGNETIC DAMPING Your balance is equipped with magnetic damping which causes the beam to come to rest quickly without affecting sensitivity or accuracy. It operates on the principle of a permanent magnetic field resisting the motion of a non-magnetic, copper damper vane attached to the beam. The pol e faces of the damping magnets lre positioned on both sides of the 6mm wide slot that the damper vane travel s in when the beam is in place. The only maintenance required is to keep these magnets free of magnetic particles which could interfere with free movement of the damper vane. Shoul d any debri s coll ect in the magnet area, it can be removed by using a piece of adhesivebacked tape. The magnetic damping is effective at all loads and will speed up weighing. HOW TO USE THE LARGE POISE (50 GRAM) The principle of the large poise consists of an accurately adjusted weight which moves parallel to the longitudinal axis of the beam and which is positioned at weight values by means of a pawl that engages notches on the beam. The poise run is from 0 to 50 grams. The equally spaced notches divide this distance into 50 equal parts so that each subdivision is equivalent to 1 gram of weight. To zero the large poise, move it to the position where the pawl, located on the rigt side of the poise, engages the first notch on the right end of the poise travel. The poise indicator will line up with the zero graduat ion. To increase weight val ues move the poise to the 1eft and 1 ine up the ind icator wi th the desired graduation. ALWAYS MAKE SURE THAT THE PAWL IS SEATED IN THE NOTCH. DO NOT ATTEMPT TO SET THE LARGE POISE POSITION EXCEPT FIRMLY SEATED IN A Always use the micrometer poise for values between the 1 gram increments l<lropnoi,p_ AT ANY NOTCH. we ig ht of the

4 APPKUACH-IU-WlluHI ~laiukl (contlnued) The bottom of the damper vane then engages the approach-to-weight leaf spring located inside the base. This leaf spring provides gradual pointer travel, through several tenths of a gram of weight, between the lower beam stop and the spring engagement point. This approach- to-wei ght area is denoted on the di al pl ate by the arrowhead on the lower portio n of the dial plate. As material is poured into the scale pan, the pointer begins to approach the pre-set weight. The beam pointer will move slowly upward past the arrowhead on the dial pl ate. This visually tell s you that very 1 ittl e more material is needed to bal ance the scal e. WHEN MAKING REPEATED WEIGHINGS IN THIS MANNER, AVOID WEIGHING ERRORS BY MAKING SURE THE POISES REMAIN IN THEIR CORRECT POSITIONS AND ARE NOT ACCIDENTALLY MOVED. The approach- to-weight leaf spring has been adj usted at the factory, by means of the hex socket set screw accessibl e from the top surface of the base. It should rarely require any adj ustment by the user. HOW TO CARE FOR YOUR BALANCE Your balance should be stored in its case when not in use. This offers the greatest protection agai nst accidental damage and dirt. To ensure that the attachment weight does not fallout of its storage well if the balance is moved, the 1 evel ing screw shoul d be in its highest position before putting the cover in place. Keep the bal ance cl ean at all par tic u1 a r 1y car e f u 1 to pre v en t tion of dirt on the pivots and the pivots or pan loop become clear with naphtha or other solvent. Blow dry. times and be the accumul a bearings. If contaminated, dry cl eani ng NEVER APPL Y OIL OR ANY LUBRICANT TO THE PIVOTS OR BEARINGS; THIS WILL LOWER THE ACCURACY OF THE BALANCE. The cover is made of high-impact thermoplastic and shaul d 1 ast for the 1 i fe of the bal ance. However, keep away from high temperatures. Do not use solvents to clean the cover. OHAUS LIMITED WARRANTY Your bal ance is warranted against defects in material s and workmanship for ninety (90) days from the date of del ivery. During that period, Ohaus will repair, or at its option, replace at no charge, parts that prove to be defective, provided that the balance is returned to Ohaus Scale Corporation. No other expressed or impl ied warranty is given by Ohaus Scal e Corporation and it shall not be 1 iabl e for any rn"r-a"' on+.;:lii1 A:IIrft:lll'lAr

5 HOW TO USE THE MICROMETER POISE (1 GRAM) The principle of the micrometer poise consists of an internally threaded weight, al so accurately adjusted, which rotates on a fixed screw or spi ndl e. The pi tch of the screw thread is 1mm and exactly matches the spacing of graduations on the 0-1 gram scale. Therefore, one complete revolution (360 ) of the poise around the spindle will move the poise longitudinally a distance equivalent to 0.1 gram of weight (10 revolutions for 1 gram). The cyl indrical surface of the micrometer poise is subdivided into 10 equal parts by means of the long horizontal 1 ines which are numbered from 0-9. Rotating the poise from one of these 1 ines to the next moves the poise longitudinally 1/10 the distance of a complete revolution or a distance equivalent to 0.01 gram of weight. A nylon screw coming in from the back of the beam is used to lock the micrometer poise in place to prevent movement during weighing. Only light finger pressure is required to tighten or loosen this screw. To zero the micrometer poise, line up the radial indicator 1 ine near the left end of the poise wi th the zero graduation on the 0-1 scal e and 1 ine up the zero 1 ine on the surface of the poise with the reading edge of the 0-1 gram scal e. To increase weight val ues, rotate the front surface of the poise upward with your thumb. This will cause the poise to travel to the 1 eft. The ind icator 1 ine near the 1 eft end of the poise will indicate tenths of a gram values while the horizontal lines on the poise will indicate hundredths of a gram. DO NOT ATTEMPT TO USE THE MICROMETER POISE WITH THE INDICATOR LINE OUTSIDE THE LIMITS OF THE 0-1 GRAM GRADUATED SCALE. WEIGHING ERRORS MAY RESULT. HOW TO WEIGH To weigh an unknown, pl ace it in the scal e pan. Move the 1 arge poi se to the first notch which causes the beam pointer to drop below the zero and then move it back one notch. Next, rotate the micrometer poise to the position which brings the beam pointer to zero. The weight of the unknown is the sum of the two poise readings. APPROACH-TO-WEIGHT FEATURE Your bal ance incorporates a uni que, approachto-weight feature developed by Ohaus Scale Corporation. To use this feature, the desired final weight is preset on the poises. This will cause the beam pointer to fall below the zero graduation.

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