Pressure Flashcards
VEGA sells pressure products for process, hydrostatic and differential pressure measurements
True
for basic applications (no digital output or display – fixed 4..20mA output)
BAR18 and BAR19
compact sensors with light ring and Bluetooth access – limited features
BAR28/29
compact sensors with display, light ring and Bluetooth access – limited features
BAR38/39
for high temperature or caustic materials
BAR81
for most applications (ceramic diaphragm)
BAR82
for high pressure
BAR83
for top down mounted hydrostatic pressure applications
BAR86 and BAR87
for low cost hydrostatic applications (no yellow housing)
WELL52
for traditional differential pressure applications – impulse lines or remote seals
DIF85
memorize one thing
Pressure (psi) = 0.446 x SG x Height (feet)
or
Pressure (bar) = 0.1 x SG x Height (meters)
You can determine the pressure range needed for the level your customer wants to measure
formula
You can determine the height of a liquid based on a pressure output and the fluids SG
formula
You can determine the SG of a product (when you have a fixed height) based on a pressure output
formula
unitless ratio of a fluids density to the density of water at 68°F
Specific Gravity
density of measured fluid ÷ 62.431 lb/ft3
Specific Gravity
What they really want is resolution and repeatability. Remember to check the Turndown of an instrument to ensure you have enough resolution.
True
full cell range ÷ desired measurement range
Turndown
We have UNLIMITED turndown but recommend 20:1 or less
True
Turndown is the ratio of the selected cell’s pressure range to the customer’s desired measurement range
True
The VEGABAR 80 Series of instruments can be used for EDP (electronic differential pressure). A Primary (master) and Secondary (slave) relationship is established between two standalone pressure devices. These are two individual pressure units that measure pressure where they are mounted (sized for the pressure they will see). The only difference between the two units is the electronics for the secondary unit. The primary device with EDP activated, receives the pressure data from the secondary unit, does the math and outputs the differential.
True
Any combination of BAR80 Series devices can be used for EDP
True
Standard electronics can be activated or deactivated for EDP
True
EDP- Only difference is the electronics module in the Secondary (SLAVE) unit
True
EDP-Each unit is sized for the pressure it will see in the application
True
EDP - Need to look at Turndown in order to make sure there is enough resolution for the customer’s measurement
True
Pressure is read in all directions and the size or shape of the vessel is irrelevant. The pressure device is only concerned about the column of fluid above the pressure cell. It is not bothered by obstructions, foam, agitation or similar things that are constraints for other technologies.
True
Remote electronics on BAR80 devices allows for better access to electronics and display
True
VEGABAR 81
Oil filled diaphragm used for high temperature applications or with corrosive process fluids where special materials need to be used
• Various diaphragm materials are available including stainless, Hastelloy, tantalum, gold, etc.
• Long lead item as all versions are manufactured in Germany
• Maximum temperature is reduced when used in vacuum (below atmospheric pressures) applications
• Recommend a 3”-150# flange or larger to minimize oil expansion effects due to temperature
• Can be used for EDP applications
• Digital communication options include HART, Foundation Fieldbus, Profibus, and Modbus
VEGABAR 82
General purpose unit used for 80% of all applications
• Ceramic diaphragm without oil filling (capacitive measurement)
• High overload protection
• Minimal re-calibration required
• Ceramic is 10x harder than stainless steel – abrasion resistant
• Can provide process temperature output (only accurate to ± 2°C)
o Temperature measurement in the cell is really for VEGA’s benefit to identify thermal shocks
o Not used for compensation of density due to temperature changes
• Best cell type for applications involving vacuum
• Single and double seal options available – belt and suspenders!
• Can be used for EDP applications
• Digital communication options include HART, Foundation Fieldbus, Profibus, and Modbus
VEGABAR 83
Use for high pressure applications
• Three different cell types based on process connection and temperature requirements
• Small process connections available
• Can be used for EDP applications
• Digital communication options include HART, Foundation Fieldbus, Profibus, and Modbus