Porometer Complete with Sensor Head 220-240V 50/60Hz, 1 ph

• Direct readout of conductance or resistance.
• Simple field calibration.
• Stores up to 1500 readings.
• Leaf stress minimised during measurements.

When the sensor head is clipped onto a leaf, a small cup is gently pressed onto the leaf surface. Water vapour diffuses out of the leaf via the stomata and this raises the humidity in the cup. The instrument times the raise in humidity between two electronically preset levels. This RH transit time is a measure of water vapour loss and is automatically converted into diffusion resistance or conductivity. Calibration should be carried out at the start of each session and when environmental conditions change significantly. A polypropylene plate with 6 groups of precisely moulded holes is used to simulate a leaf. The diffusion resistance of each group is known from the physical dimensions of the holes. The instrument is calibrated using these values, and will also give a warning if changing conditions require recalibration.