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 THE NEED
H2S is entrained in liquid sulfur as it runs into the sulfur pit. Polysulfide compounds in the liquid sulfur break down with time to release H2S. H2S from these sources collects in the vapor space above the sulfur where it could exceed both toxic limits and the lower explosive limit. To prevent a dangerous H2S concentration from accumulating, most pits are air purged to keep H2S levels low. Compressed air is expensive, and most plants run with an excessively low H2S level to be on the safe side. In addition to the H2S hazards, the liquid sulfur itself can catch fire thereby spewing high concentrations of SO2 gas into the vapor space above the liquid sulfur. For safety purposes, it is necessary to monitor the vapor space above the liquid sulfur for H2S and SO2 gases.
THE SOLUTION
The AMETEK 881-NSL (No Sample Line) Sulfur Pit Analyzer measures H2S in the vapor space above the sulfur pit. Substantial cost savings can be made using this reliable analyzer to control the H2S level giving an adequate safety margin. Some customers also want to measure SO2 in the sulfur pit, reasoning that the presence of SO2 may indicate an incipient fire.
SUPERIOR Benefits
Direct Process Mounting Design
Sample line plugging is the number one maintenance problem for all sulfur recovery analyzers. The 881-NSL is installed directly on your sulfur pit lid; sample gas is drawn directly into the analyzer and returned to the process through the same sample tap. There is no need for a costly, heated sample line.
Long Term Reliability
The 881-NSL photometer combines an extraordinary long lamp life (estimated 5 years!) with many innovative features designed to minimize maintenance and increase reliability. The 881-NSL is equipped with anti-clogging blowback features. Any out-of-range condition automatically initiates air blowback to clear the sample system. The 881-NSL employs a heated air aspirated sample system eliminating the need for moving parts thereby increasing system reliability. In addition, the detector is a solid state design with no moving parts. The analyzer continuously monitors itself for proper operation and has built-in alarm features.
Improved Plant Safety
Achieved through continuous monitoring of the H2S and SO2 content in the sulfur pit atmosphere to warn of buildup of explosive concentrations of H2S in the space above the liquid sulfur or the existience of a incipient sulfur fire.
| Specifications |
| Methodology: |
Non-dispersive ultraviolet |
| Measurement Range: |
0 to 1% SO2, 0 to 5% H2S typically. Other ranges on request. |
| Accuracy: |
H2S and SO2: +2% full scale |
| Sensitivity: |
+0.15% full scale |
| Reproducibility: |
+1% of full scale |
| Speed of Response: |
90% in less than 15 seconds, typical |
| Sample Flow: |
2 LPM typical |
| Ambient Temperature: |
-20ºC to 50ºC (-4ºF to 122ºF) |
| Utilities |
| Electrical: |
115/230 VAC 50/60 Hz 690W |
| Instrument Air: |
490 to 700 kPa (70 to 100 psig) |
| Steam: |
(optional ball valve jacket): 515 to 690 kPa (75 to 100 psig) |
| Outputs: |
Four (4) 4-to-20 mA, self-powered, linear, 1200 ohms load proportional to H2S, SO2
One (1) digital, common fail-safe alarm for system fault
One (1) digital input for remote auto calibration |
| Digital Communication: |
RS485 serial port. Remote dial-in capabilities available with AMETEK Western Research software |
| Zero: |
Automatic with instrument air at 70 to 100 psig 0.1 nm3/h (3 SCFH) |
| Noise: |
+0.5% full scale |
| Zero Drift: |
Less than +0.5% of full scale in 24 hours through periodic automatic zero standardization |
| Calibration: |
Automatic with span filter, manually operated from the controller |
| Process Sample Pressure: |
Not critical |
| Customer-Supplied Items: |
2 in.-150 lbs. or DIN equivalent RF stainless steel flange connection |
| Enclosure Material: |
316 stainless steel |
| Approvals and Certifications: |
UL/CSA General Safety Requirements
UL/CSA Class I, Division 2, Groups A, B, C and D
ATEX II 2 G, EEx p mde [ib] IIC T3
Complies with all relevant European Directives |
| Physical Dimensions: |
(H x W x D): 1161 x 1037 x 305 mm (46 x 41 x 12 in.) |
| Approximate Weight: |
115 kg (250 lbs.) |
Specification Sheet
Technical Paper
Other
- UL/CSA General Safety Requirements
- UL/CSA Class I, Division 2, Groups A, B, C and D
- ATEX II 2 G, EEx p mde [ib] IIC T3
- Complies with all relevant European Directives
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