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
VEGABAR 86 and VEGABAR 87
Top down mounted device for hydrostatic pressure measurements
• Available with ceramic or metal diaphragms
• Cab be configured with cable or tube
• Can be used for EDP applications
• Digital communication options include HART, Foundation Fieldbus, Profibus, and Modbus
VEGAWELL 52
Inexpensive Top down mounted device for hydrostatic pressure measurement
• No yellow housing or local display – electronics are in the component that is submerged in the fluid
• Very long cables available for direct mount to control cabinet
• Ceramic cell (see VEGABAR82 comments above)
• Available configurations can be all plastic, coated or stainless steel with different cable options
• Digital communication option is HART
VEGADIF 85
Traditional differential pressure device for measuring the difference between two pressure points
• Main applications use is with HIGH static pressure and SMALL measurement range
• Available for use with capillary lines (remote oil filled seals) or impulse lines (using process fluid to transfer the pressure
• Remote seals with capillaries are usually the same length to help with “speed of response”. You will usually see a coil of the capillary hanging at the low measurement point.
• External environment affects the oil or process flowing in the connection lines – heat makes it expand and cool contract
• Can have connections on one or both sides
• Measures in absolute pressure but since we look at the difference it doesn’t matter
• 3-way and 5-way valve manifolds are available
When selecting an ABSOLUTE pressure cell to measure vacuum, the best range to choose would be?
0…15 psi
VEGABAR with only 4…20mA output has no lighting.
True
What is the name of the 3-key operation with VEGABAR?
VDMA
The new VEGABAR series instruments are not suitable for hydrostatic measurements.
False
VEGABAR 29 has a ceramic measuring cell.
False
Metal separating diaphragms can be made of many different materials depending on application.
True
To minimize drift due to oil expansion and contraction, we recommend the minimum flange size to be?
3” (DN75)
The VEGA ceramic cell only uses medical white oil filling for hygienic applications.
False
About how many times harder are ceramic diaphragms than stainless steel?
10
The VEGA ceramic diaphragm can be used in ALL pressure applications.
False
Atmospheric pressure is ……
the pressure exerted by the air above
Gauge pressure is…..
the pressure measured relative to atmospheric pressure
Differential pressure is…..
the difference in pressure between two points of measurement
Hydrostatic pressure is…..
downward pressure exerted by fluid based on its density and weight
VEGA’s Hydrostatic products are used in the following applications
Flotation Cells
Top Down Storage Tanks
Shipbuilding
About how many times harder are ceramic diaphragms than stainless steel?
10
Which of the following is NOT a linear level measurement using pressure?
inH2O
TORR
mmHG
All of the above
True or False: EDP easily replaces DP systems if capillaries are less than 10 ft and range is less than 10 psi.
False
The specific gravity (SG) of a substance refers to its…
Density
True or False: VEGABAR 29 has a ceramic measuring cell
False
When should a “Double Seal” be suggested for the VEGABAR 82?
Always
Is a relative pressure measurement a differential pressure measurement?
Yes
True or False: Metal separating diaphragms can be made of many different materials, depending on the application.
True
What is VEGA’s recommended turndown ratio?
20:1
What is the name of the 3-key operation with the VEGABAR 10, 20, and 30 series sensors?
VDMA
With hydrostatic level, linearization is used if the sensor is NOT mounted in the tank bottom.
False
True or False: The VEGA ceramic cell diaphragm can be used in ALL pressure applications.
False
Which of the following instruments can NOT be configured for a differential pressure measurement?
VEGAWELL52
What is the turndown for a 5 … 10 psi measurement, using a 0 … 15 psi cell?
3:1
True or False: Currently, the VEGABAR 20 and 30 series sensors with only 4 … 20 mA output have no lighting.
True
Can pressure be used to measure density?
Yes
If the temperature of a process changes quickly, the hydrostatic pressure measurement output… [Select all that apply]
Increases
Decreases
True or False: The VEGABAR 82 with its 2 temperature sensors makes it the best instrument for measuring fluids with changing densities.
False
What is the pressure reading at full vacuum with an absolute measurement cell?
0 Bar
Which sensor is used for high temperature applications?
VEGABAR 81
What would be the best cell range to use for a requested measurement range of 110 … 350 psi? [Select all that apply]
0-300 psi
0-25bar
Is a second current output available with an EDP configuration of a VEGABAR 81 and a VEGABAR 83?
Yes
If a hydrostatic measurement is not reading correctly, what could be the issue?
Temperature of the process
Density of the process
Pressure cell range
What is Absolute Pressure?
Measurement against a vacuum
Is process temperature an available output from all the VEGABAR 80 series instruments?
No
Can differential pressure be used to measure interface?
Yes
In an EDP setup can the pressure reading from both cells be assigned as HART variables?
No
When selecting a chemical seal, we should suggest a minimum flange size of…
3”-150#
True or False: The VEGADIF 85 measures in “Absolute” pressure ranges
True
