| no longer | 24 | temporal |
| for use with drinking water | 18 | purpose |
| under operating conditions | 4 | other |
| boiler → be → safe | 145 |
| boiler → be safe to → use | 7 |
| boiler → be safe to → operate | 4 |
| negative | neutral | positive |
| 0.087 | 0.453 | 0.460 |
| Raw frequency | 156 |
| Normalized frequency | 0.809 |
| Modifier score | 0.500 |
| Perplexity | 190.035 |