HPV 茎流量传感器/Sap Flow Sensor
HPV茎流量传感器是一款校准型、低成本的热脉冲液流传感器，输出校准液流量、热速、茎水含量、茎温等数据，功耗低，内置加热控制，同时改善了传统的加热方式，其原理采用热脉冲速率法，测量范围：-200~+1000cm/hr(热流速度)或-100~+2000cm3/cm2/hr (茎流通量密度)，可广泛用于于茎流量监测、植物茎流蒸发计算、植物茎流蒸腾量、植物灌溉等
植物茎流是树木内部的“水”运动，而蒸腾是从叶片通过光合作用蒸发流出的水分。树液流量和蒸腾量之间有很强的关联性，通常理解是同一回事。但是，严格地说，它们是不同的，这体现在它们是如何被测量的。
SAP流量以L/hr（或每天、每周等）为单位进行测量。蒸腾量以每小时、每天、每星期等毫米（mm）为单位测量。
蒸散量=蒸腾量+蒸发量
蒸腾量以毫米为测量单位，可与降雨量以毫米计作比较。随着时间的推移，降雨量（水输入）应与蒸腾量（输出）相匹配。如果蒸腾作用更高，通常是树木作物的蒸腾作用，那么这种差异必须通过灌溉来弥补。
蒸发量（evaporation），蒸发量是指在一定时段内，由土壤或水中的水分经蒸发而散布到空中的量。
1mm(降雨量)=1㎡地面1kg水
1mm(蒸腾量)=1㎡叶面积的1升树液流量（水）
例如：在果园和葡萄园等有管理的树木作物系统中，蒸发量与蒸腾量相比非常小。因此，为了简化测量，通常忽略蒸发量，将蒸腾量取为平均蒸散量（ETo）。
茎流量传感器广泛应用
计算总流量
低液流和零液流速率
反向液流速率
夜间水分损失
根茎液流速度
贫瘠生态系统及干旱
径向液体流速
葡萄藤的液流
茎流量传感器技术指标
测量范围：-200~+1000cm/hr(热流速度)
分辨率：0.001cm/hr
准确度：±0.1cm/hr
探针尺寸：φ1.3mm*L30mm
温度位置：外10mm，内20mm
针距：6mm
探针材质：316不锈钢
温度范围：-30~+70℃
响应时间：200ms
加热电阻：39Ω，400J/m
电源：12V DC
电流：空闲5mA, 测量<270mA
线缆：5m，*大60m
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