diff --git a/frappy_psi/pfeiffer.py b/frappy_psi/pfeiffer.py
index 2511ef4..5a9e09f 100644
--- a/frappy_psi/pfeiffer.py
+++ b/frappy_psi/pfeiffer.py
@@ -18,7 +18,7 @@
 # *****************************************************************************
 """pfeiffer TPG vacuum pressure reading"""
 
-from frappy.core import StringIO, HasIO, Command, StringType, IntRange, \
+from frappy.core import StringIO, HasIO, IntRange, \
     IDLE, WARN, ERROR, Readable, Parameter, Property
 from frappy.errors import CommunicationFailedError
 
@@ -43,7 +43,7 @@ class IO(StringIO):
 
 class Pressure(HasIO, Readable):
     value = Parameter(unit='mbar')
-    channel = Property('channel number', IntRange(1,2), default=1)
+    channel = Property('channel number', IntRange(1, 2), default=1)
 
     STATUS_MAP = {
         '0': (IDLE, ''),
@@ -56,7 +56,7 @@ class Pressure(HasIO, Readable):
     }
 
     ioClass = IO
-    
+
     def read_value(self):
         reply = self.communicate(f'PR{self.channel}')
         status, strvalue = reply.split(',')