Methods and systems for limiting water within a photoionization detector
Methods and systems for detecting and limiting the water in a photoionization detector are provided. The method may include powering off a lamp configured to ionize particles of air. The method may also include monitoring a signal from the photoionization detector. The signal may be monitored based on a current between a signal electrode and a bias electrode. In an instance the signal is above a signal threshold, the method may also include electrolyzing one or more particles of water present in the photoionization detector by closing a leakage switch in order to allow current to flow through the bias electrode and the signal electrode. In an instance the signal is below the signal threshold, the method may include powering on the lamp to begin photoionization detection. Corresponding systems are also provided.
1 . A photoionization detector (PID) comprising:
a bias electrode;
a signal electrode;
a processing circuitry configured to:
monitor a signal between the signal electrode and the bias electrode, and
determine whether the signal is above a threshold to indicate that water is present in the PID and, in an instance in which the signal is above the threshold, the processing circuitry is further configured to close a leakage switch to connect the signal electrode to at least one of a reference voltage or a ground to allow current to flow through the bias electrode and the signal electrode to electrolyze one or more particles of water present in the PID.
2 . The photoionization detector of claim 1 , further comprising a lamp configured to ionize particles of air.
3 . The photoionization detector of claim 2 , wherein in an instance the signal falls below the threshold, the lamp is configured to power on.
4 . The photoionization detector of claim 2 , further comprising a lamp switch configured to provide power to the lamp.
5 . The photoionization detector of claim 2 , wherein the lamp is a short-wavelength ultraviolet (UV) lamp.
6 . The photoionization detector of claim 1 , wherein the photoionization detector is configured to electrolyze one or more particles of water within a housing of the photoionization detector.
7 . The photoionization detector of claim 1 , wherein the threshold is from 3 millivolts to 300 millivolts.
8 . The photoionization detector of claim 1 , further comprising a voltage bias switch configured to provide a voltage to the bias electrode, wherein the voltage bias switch and the leakage switch are closed to electrolyze water in the PID.
9 . A signal processing device for limiting water accumulation in a photoionization detector (PID) comprising:
an analog-to-digital converter for monitoring a signal between a bias electrode and a signal electrode of the PID;
a processing circuitry for determining whether the signal is above a threshold to indicate that water is present in the PID; and
a leakage switch, wherein, in an instance in which the signal is above the threshold, the leakage switch is closed to allow current to flow through the bias electrode and the signal electrode by connecting the signal electrode to at least one of a reference voltage or a ground to electrolyze one or more particles of water present in the PID.
10 . The signal processing device of claim 9 , further comprising a microcontroller and/or integrated circuit configured to integrate the signal.
11 . The signal processing device of claim 9 , further comprising a lamp switch and a voltage bias switch, wherein, when the lamp switch, the leakage switch and the voltage bias switch are open, the signal processing device is configured to identify a non-zero signal indicating a signal processing circuit fault in the signal processing device.
12 . The signal processing device of claim 11 , wherein an error message is displayed visually, audibly, or tactically based on the signal processing circuit fault in the signal processing device.
13 . The signal processing device of claim 9 , wherein the signal is a current signal or a voltage signal.
14 . The signal processing device of claim 9 , wherein the threshold is from 3 millivolts to 300 millivolts.
15 . The signal processing device of claim 9 , wherein the processing circuitry comprises an op-amp having a resistor, and a capacitor arranged to convert detector current into a voltage for monitoring the PID.