Vibration Engineering 1 (Final Term) PDF

VIBRATION ENGINEERING # 1 (FINAL TERM) Prepared By: Mark Ronie C. Viscarra DATABASE DEVELOPMENT Valid data are an absolute prerequisite of vibration monitoring and analysis. W i t h o u t a c c u r a t e a n d complete data taken in the appropriate frequency range, i t i s i m p o s s i b l e...

VIBRATION ENGINEERING # 1 (FINAL TERM) Prepared By: Mark Ronie C. Viscarra DATABASE DEVELOPMENT Valid data are an absolute prerequisite of vibration monitoring and analysis. W i t h o u t a c c u r a t e a n d complete data taken in the appropriate frequency range, i t i s i m p o s s i b l e t o interpret the vibration profiles obtained from a machine-train. This is especially true i n a p p l i c a t i o n s t h a t u s e microprocessor/computer- b a s e d s y s t e m s. T h e s e systems require a database t h a t s p e c i f i e s t h e m o n i t o r i n g p a r a m e t e r s ,  WHAT IS EQUIPMENT INFORMATION SHEET? MACHINE PROCESS AND DATA COLLECTION Database development can be a c c e l e r a t e d a n d i t s accuracy improved by first creating detailed e q u i p m e n t a n d p r o c e s s information sheets that f u l l y d e s c r i b e e a c h machine and system to be monitored. Equipment Information Sheets T h e f i r s t s t e p i n establishing a database TYPE OF OPERATION The EIS should define the type of operation (i.e., constant speed or variable speed) that best describes the normal operation of each machine-train. This information allows the analyst to determine the best method of monitoring and evaluating each machine. TYPE OF OPERATION The EIS should define the type of operation (i.e., constant speed or variable speed) that best describes the normal operation of each machine-train. This information allows the analyst to determine the best method of monitoring and evaluating each machine. CONSTANT SPEED MACHINERY Few, if any, machines found in a m a n u f a c t u r i n g o r production plant are truly constant speed. While the nameplate and specifications m a y i n d i c a t e t h a t a machine operates at a fixed s p e e d , i t w i l l v a r y slightly in normal operation. The reason for speed variations in constant-speed machinery is variation of process load. For example, a centrifugal pump’s load will vary due to the viscosity of the VARIABLE SPEED MACHINERY For machinery and process systems that have a wide range of operating speeds, the data sheet should provide a minimum and maximum speed that can be expected during normal operation. In addition, a complete description of other variables (e.g., product type) that affect the machine’s speed should be included. CONSTANT VERSUS VARIABLE LOAD As with constant-speed machines, true constant-load machines are rare. For the few that may be specified as having constant load, there are factors that cause load changes to occur. These factors include variations i n p r o d u c t , o p e r a t i n g conditions, and ambient environment. These variations will have a direct, and often d r a m a t i c , i m p a c t o n a machine’s vibration profile. MACHINE COMPONENTS T h e E I S s h o u l d p r o v i d e information on all components (e.g., bearings, gears, gear- boxes, electric motors, pumps) that make up the machine- t r a i n. B e c a u s e t h e s e c o m p o n e n t s g e n e r a t e vibration energy and unique frequency components, this information is essential for proper analysis. At a minimum, the information sheet must include detailed bearing i n f o r m a t i o n , p a s s i n g MACHINE COMPONENTS BEARING All bearings in a machine- train must be identified. For example, rolling-element bearing data must include the manufacturer’s part number, bearing geometry, and the unique rotational frequencies that it will g e n e r a t e. R o t a t i o n a l f r e q u e n c i e s c a n b e determined by using the bearing pa r t n u m b e r t o l ook them up in the database MACHINE COMPONENTS JOURNAL BEARING MACHINE COMPONENTS ROLLER BEARING BEARING CODE REFERENCE MACHINE COMPONENTS PASSING FREQUENCIES A l l c o m p o n e n t s t h a t g e n e r a t e a p a s s i n g f r e q u e n c y m u s t b e included on the information s h e e t. S u c h c o m p o n e n t s include fan or compressor b l a d e s , v a n e s o n p u m p impellers, rotor bars in electric motors, and gear teeth on both the pinion and bullgear in a gear set. The number of vanes, blades, and g e a r t e e t h m u s t b e MACHINE COMPONENTS NAMEPLATE DATA E a c h m a c h i n e - t r a i n component has a vendor’s nameplate permanently attached to its housing. The E I S s h o u l d i n c l u d e a l l nameplate data, including the serial number that uniquely identifies a machine or component. Knowing the serial number allows detailed information on a machine or component to be MACHINE COMPONENTS NAMEPLATE DATA PROCESS INFORMATION SHEETS A process information sheet (PIS) should be developed for each machine-train and production p r o c e s s t h a t i s t o b e included in a predictive maintenance program. These data sheets should include all pr oc e s s v a r i a b l e s t h a t affect the dynamics and vibration profiles of the monitored components. Many production and process systems handle a wide range DATABASE SETUP The input-data requirements and steps needed to set up the database for a computer- based vibration monitoring program vary depending on the analyzer/software vendor and the system’s capabilities. This section d i s c u s s e s t h e i n p u t required for such a data- b a s e. H o w e v e r , t h i s information should be used in conjunction with the vendor’s users’ manual to ensure proper ANALYSIS PARAMETER SETS The software used to manage the data incorporate what are referred to as analysis parameter sets (APSs). APSs define and specify machine dynamics, components, and failure modes to be monitored. ANALYSIS PARAMETER SETS The software used to manage the data incorporate what are referred to as analysis parameter sets (APSs). APSs define and specify machine dynamics, components, and failure modes to be monitored. ANALYSIS TYPE As discussed previously, data-collection analyzers i n c o r p o r a t e a n a l y s i s parameter sets that allow the user to control the data-gathering process. APSs p r o v i d e t h e o p t i o n o f selecting either frequency analysis for fixed-speed m a c h i n e r y o r o r d e r s analysis for variable-speed machinery. VARIABLE SPEED: ORDERS ANALYSIS In a variable-speed machine, t h e u n i q u e f r e q u e n c i e s generated by components such as bearings and gear sets do not rem a i n c on s t a n t. As the speed changes, the unique frequency components vary in direct proportion to the speed change. For this type of machinery, the a n a l y z e r ’ s o r d e r s a n a l y s i s op t i on i s u s e d t o automatically adjust each of the filters used to RESOLUTION Resolution is the degree of s p a c i n g o f v i s i b l e frequency components in the vibration signature and is p r o p o r t i o n a l t o t h e bandwidth. The equation for resolution follows: