18. In Winter, naturally, they closed the Shutters, But in Kolomna,5 Summer Nights are hot, And so they left them open; the Muse stutters With Shame to mention “Pale Diana” (not, I’m sure, that She is swarthy – my heart flutters As fast as Any one’s, at her cold, fruitless Lot) But while her Mama snored, our chaste Parasha Prayed to the night6 to make her Life no harsher --- With D impeller for fan with guide vanes: The axial fans with the D impeller is equipped with guide vanes for higher pressures and efficiency. The impeller is made of sea water resistant alum and has variable pitch to easier suit different capacities and pressures. Due to the guide vanes the fan can achieve pressures up to 1600 Pa.