交错排列的旋涡
由于d和St是常数，而流速v与管内平均流速v0有固定关系(v0=v/(1-1.25d/D))，测得旋涡分离频率f就测得管内平均流速v0，从而测得体积流量。一段时间内分离旋涡的个数N与流过流体的体积V之比(单位体积对应的旋涡数)称为仪表系数K：
K=N/V      公式(3)
FA80M/FA80T系列涡街流量计采用装设于柱体后面的压电探头检测旋涡分离频率。FA80M流量传感器输出与流量成比例的电压脉冲频率信号，FA80T流量变送器输出的是变换成与流量成比例的4-20mA标准电流信号。
 
流量计选型
涡街流量计的选型正确与否，将直接影响到仪表能否正常运行，因此设计单位和用户应首先做好以下准备工作，以保证选型合理、正确：
确认仪表用途，一般分为流量控制、一般计量或用于贸易结算；
2. 确定在管道上的具体安装位置，找出可能影响仪表正常工作的环境因素；
3. 认真核对测量流体的工艺参数如：压力、温度、粘度、流量范围等。
主要技术指标
1公称口径(mm)
  满管式：DN15、20、25、<span style="FONT-FAMILY: Arial; FONT-SIZ

特点：
热响应时间少，减小动态误差；
可弯曲安装使用；
测量范围大；
机械强度高，耐压性能好；
工作原理：
热电偶的电极由两根不同导体材质组成。当测量端与参比端存在温差时，就会产生热电势，工作仪表便显示热电势所对应的温度值。
技术参数：
产品执行标准：IEC584 IEC1515 JB/T5582-91
GB/T16839-1997
常温绝缘电阻:
热电偶在环境温度为20±15℃，相对湿度不大于80%，试验电压为500±50V（直流）电极与外套管之间的绝缘电阻≥ 1000MΩ.m。
即: 1M长的试样的绝缘电阻为1000 MΩ；
10M长的试样的绝缘电阻为100 MΩ；PCI-20013A-1 Cable Digital, 16-channel, ground-plane cable, standard-density, 34-conductor. Length is 6 feet(1.8m). Use with PCI-20018T-1 and PCI-20048T-1 only.
PCI-20015A-1 Cable Analog, 16/8 channel, shielded cable, standard-density, 26-conductor. Length is 4 feet(1.2m)
PCI-20018T-1 Termination Panel 8-channel, oto-isolator, digital I/O termination panel.
PCI-20020M-1 Option Module 1-channel trigger/Alarm, option module.
PCI-20021M-1B Option Module 8-channel 12-bit, analog voltage output module.
PCI-20023M-1 Option Module 8-channel, very higy-speed, 12-bit, analog b, 8-channel, option module. Use with standard density analog cables.
PCI-20024T-1 Termination Panel Analog Customizer termination panel. Use wity high-density, 26-conductor cable.
PCI-20024T-2 Termination Panel Analog Customizer termination panel. Use wity standard-density, 26-conductor cable.
PCI-20025T-1 Termination Panel 32-channel digital Customizer termination panel. Use with up to 2 high-density, 34-conductor cables. A-B  1756L55M13 模块
PCI-20025T-2 Termination Panel 32-channel digital Customizer termination panel. Use with up to 2 standard-density, 34-conductor cables.
PCI-20028A-3 Bracket Strain-relief cable-mounting bracket.
PCI-20029A-1 Enclosure Quad termination panel enclosure with cover.
PCI-20031M-1 Option Module Analog b expander/sequencer option module. Use with up to two standard-density, 26-conductor cables.
PCI-20033A-1 Accessory Module extender to facilitate PCI-20002M-1 module calibration.
PCI-20036A-1 Cable Digital, 16-channel, unshielded cable, standard-density, 34-conductor. Length is 4 feet(1.2m)
PCI-20041C-2A ISA Board Expandable A-B  1756L55M13 模块  ISA high-perbance board with interrupts, pacer clock, 32 points digital I/O, and inter-board bus. Use with standard-density, 34-conductor cables. 
PCI-20041C-3A ISA Board Expandable ISA high-perbance board with DMA, interrupts, pacer clock, 32 points digital I/O, and inter-board bus. Use with standard-density, 34-conductor cables. 
PCI-20048T-1 Termination Panel 16-channel, opto-isolator digital I/O termination panel. Use with PCI-20013A cable.
PCI-20061A-1 Cable Digital, 16-channel, ground-plane cable. Length is 6 feet(1.8m)
PCI-20087W-1A ISA Board ISA digital I/O, 40-channel, TTL compatible board. Includes MasterLink software libraries. Use withstandard-density, 34-conductor cable. 
PCI-20093W-1A ISA Board ISA analog output board, 8 channels, voltage or current. Includes Master Link sofware libraries. Use with standard-density, analog cable.
PCI-20098C-1F ISA Board ISA multifunction IO board; 45kHz. Includes Master Link software libaries.
PCI-20098C-2F ISA Board ISA multifunction IO board; 100kHz. Includes Master Link software libraries. Use with high density analog and digital cables.  A-B  1756L55M13 模块
PCI-20201M-2 Option Module Memory expansion option module for use with PCI-20202C-1 and PCI-20202C-2 SmartCarrier.
PCI-20201M-3 Option Module High-speed memory expansion option module for PCI-20202C-3 SmartCarrier.
PCI-20202C-1 ISA Board SmartCarrier processor board with DSP and 28MHz clock. Includes DSPView Software.
PCI-20202C-2 ISA Board SmartCarrier processor board with DSP and 40MHz clock. Includes DSPView Software.
PCI-20202C-3 ISA Board SmartCarrier processor board with DSP and 50MHz clock. Includes DSPView Software.
PCI-20303T-1 Termination Panel Euro-Style, 16/8-channel, analog termination panel. Use with PCI-20310A-1 analog cable. A-B  1756L55M13 模块
PCI-20303T-2 Termination Panel Euro-Style, thermocouple, 7-differental channel, analog termination panel. Use with PCI-20310A-14 analog cable.
PCI-20304T-1 Termination Panel Euro-Style, 16/8 bs,2 outputs, analog termination panel for high-desity connectors. Use with PCI-20008A-1 high-density, 26-conductor cable. 
PCI-20304T-2 Termination Panel Euro-Style, thermocouple, 7 differential bs, 2 outputs, analog termination panel for high-density connectors. Use with PCI-2008A-1 high-density, 26-conductor cable.
PCI-20305T-1 Termination Panel Euro-Style, digital, 16-channel termination panel. Use with PCI-20311A-1 digital cable. A-B  1756L55M13 模块
PCI-20306T-1 Termination Panel Euro-Style, digital, 16-channel termination panel for high-desity connectors.Use with high-density, 34-conductor cables.
PCI-20307T-1 Termination Panel Euro-Style, digital, 16-channel expansion termination panel. Use with PCI-20306T-1(expander cable included).
PCI-20309A-1 Accessory Accessory kit with mounting hardware for up to five Euro-Style, 3U-size termination panels.
PCI-20310A-1A Cable Analog, shielded cable, standard-density, 26-conductor cables. Length is 6.5 feet(2m).
PCI-20311A-1A Cable Digital, ground-plane cable. Length is 6.5 feet(2m).
PCI-20324T-1 Termination Panel Opto, Euro-Style, 8-channel, standard-connector termination panel. Use with PCI-20311A-1 digital cable. A-B  1756L55M13 模块
PCI-20324T-2 Termination Panel Opto,Euro-Style,quick-disconnect,8-channel,standard-connetcor termination panel.Use with PCI-20311A-1 digital cable.
PCI-20325T-1 Termination Panel Opto,Euro-Style, 8-channel high-density connector termination panel.Use with PCI-20009A-1 high-density digital cable.
PCI-20325T-2 Termination Panel Opto, Euro-Style, quick-disconnect, 8-channel, high-density connector termination panel. Use with PCI-20009A-1 high-density digital cable. 
PCI-20326T-1 Termination Panel Opto, Euro-Style, 8-channel, expander termination panel. Use with the PCI-20324T or the PCI-20325T. A-B  1756L55M13 模块
PCI-20326T-2 Termination Panel Opto,Euro-Style,quick-disconnect, 8-channel, expander termination panel. Use with the PCI-20324T or the PCI-20325T.
PCI-20338A-1 Power Supply Power supply, 5VDC output at 6A. Universal line voltage, 85 to 264VAC.
PCI-20339A-1 Enclosure Rack-mount enclosure for PCI-5B01-1 or PCI-20048T-1.
PCI-20341M-1A Option Module 4-channel, 16-bit analog b option module. Use with standard-density, 26-conductor cable. A-B  1756L55M13 模块
PCI-20343A-1 Cage Tabletop enclosure for up to 3 Euro-Style termination panels.
PCI-20353T-1 Termination Panel 5B,Euro-Style,8-channel,high-density/standard connerctor, termination panel. Use with standard- or high-density cables.
PCI-20353T-2 Termination Panel 5B, Euro-Style,  8-channel, high-density/standard connerctor, termination panel, with quick disconnect terminal blocks.  Use with standard- or high-density cables.
PCI-20354T-1 Termination Panel 5B, Euro-Style, 8-channel expansion termination panel. Use with PCI-20353T-1.