Maintenance of M&C SP2006-H/DIL Sampling Probe

M&C SP2006-H/DIL Dilution Probe Complete Maintenance and Troubleshooting Guide

In the field of process gas analysis, continuous sampling of high temperature, high humidity, dusty, and corrosive gases has always been a technical challenge. The SP2006-H/DIL series dilution probes launched by M&C TechGroup are based on the mature SP2000-H platform and adopt a dilution principle combining critical orifice plates and injectors, effectively solving the problems of traditional sampling probes being prone to clogging and frequent maintenance. This article is aimed at on-site maintenance engineers and system integrators, comprehensively analyzing the structural principles, installation points, startup process, daily maintenance, and typical troubleshooting of SP2006-H/DIL and SP2006-H280/DIL dilution probes, helping you quickly locate problems and restore normal equipment operation in actual working conditions.

Product Overview and Application Scenarios

SP2006-H/DIL is an electrically heated gas sampling dilution probe with a maximum heating temperature of 180 ° C (SP2006-H280/DIL can reach 280 ° C). The core design goal is to dilute the sample gas with clean diluent gas (such as nitrogen or instrument air) in a fixed ratio without changing the measurement components, thereby reducing the dew point of the sample gas, avoiding condensation corrosion, and reducing the maintenance of downstream analyzers.

Typical applications include:

Continuous monitoring of toxic gases (such as HCl, NH3, HF)

Measurement of moisture in flue gas emissions

Sampling of process gases containing high concentrations of dust or viscous particles

Sensitive processes requiring extremely low sampling flow rates (as low as 1.4 Nl/h)

This probe adopts a modular design and can be equipped with various accessories such as pre filters, blowback function, bypass injectors, heating ball valves, and pressure storage tanks according to on-site needs, adapting to process conditions ranging from atmospheric pressure to 2 bar absolute pressure.

Working principle: Critical orifice plate+injector dilution

Understanding the core technology of SP2006-H/DIL is the foundation of troubleshooting. The dilution unit is based on the principle of ultrasonic critical flow: when the pressure difference on both sides of the critical orifice plate is ≥ 500 mbar (i.e. outlet absolute pressure ≤ 520 mbar), the gas flow rate through the orifice plate depends only on the upstream pressure and is independent of downstream pressure fluctuations. This feature ensures a constant dilution ratio.

The specific process is as follows:

After being regulated by a precision pressure reducing valve, a portion of the diluted gas (such as N ₂) enters the injector and generates a high-speed jet at the injector nozzle, forming negative pressure.

This negative pressure acts on the outlet end of the critical orifice plate, maintaining the pressure difference between the front and rear of the orifice plate above the critical pressure difference.

The sample gas is drawn into the critical orifice plate through the process pipeline, probe tube, and filter element, and mixed with the dilution gas in a fixed proportion.

The mixed diluted sample gas is sent from the probe outlet to the downstream analyzer.

The dilution ratio is determined by the pore size of the critical orifice plate. The dilution ratios and sample gas flow rates corresponding to standard orifice plate types a~g are as follows (injector type I, dilution gas flow rate 480-600 Nl/h):

Orifice plate model a b c d e (standard) f g

Dilution ratio 500:1 200:1 100:1 50:1 30:1 20:1 10:1

Sample gas flow rate (Nl/h) 1.4 2.7 5.5 11 19 28 55

If using injector type II, the dilution ratio can be extended to 2000:1. Users can also adjust the dilution ratio within a certain range by fine-tuning the dilution gas pressure (-5%~+30%).

Key engineering points:

The vacuum degree at the outlet of the injector must be greater than 0.6 bar (absolute pressure<0.4 bar), otherwise the critical condition is not met and the dilution ratio will fluctuate.

Common reasons for insufficient vacuum degree include low dilution gas pressure, clogged injectors, excessively long or narrow sampling outlet pipelines.

Manual recommendation: The maximum length of the outlet sampling tube for injector type I is 50 meters for 1/4 inch and 150 meters for 3/8 inch; the diameter of injector type II needs to be correspondingly increased due to its high flow rate.

Quick search and interpretation of technical parameters

From the perspective of on-site maintenance, the following parameters are the most noteworthy:

Parameter SP2006-H/DIL SP2006-H280/DIL

Maximum heating temperature 180 ° C 280 ° C

Diluted gas inlet pressure 4.5~16 bar g (approximately 3 bar after pressure reduction) is the same as the left

The vacuum degree requirement for the sample gas outlet is>0.6 bar (absolute pressure<0.4 bar), same as the left

Process pressure range 0.9~2 bar abs same as left

Liquid receiving material SS316Ti, quartz glass FKM、 Graphite on the left

Weight approximately 30 kg on the left

Heating power 800 W (230V or 115V optional) same as left