Index: firmware/App/Modes/Dialysis.c
===================================================================
diff -u -r101bf85b0b425e919b01b4b7fabcbd15fd5bbde5 -rde169e7374f6c7a737995ac8c6c3953dc5c75aa7
--- firmware/App/Modes/Dialysis.c	(.../Dialysis.c)	(revision 101bf85b0b425e919b01b4b7fabcbd15fd5bbde5)
+++ firmware/App/Modes/Dialysis.c	(.../Dialysis.c)	(revision de169e7374f6c7a737995ac8c6c3953dc5c75aa7)
@@ -35,9 +35,11 @@
 
 // ********** private definitions **********
 
-#define MAX_UF_RATE_ML_PER_MIN                  45.83                           ///< Maximum ultrafiltration rate in mL/min (2750 mL/hr).
+#define MAX_UF_RATE_ML_PER_HOUR                 2750.0                          ///< Maximum ultrafiltration rate in mL/hour
+#define MAX_UF_RATE_ACCURACY_ERROR_ML_HR        100.0                           ///< Maximum ultrafiltration rate accuracy error in mL/hr over each hour of treatment.
+#define MAX_UF_RATE_ACCURACY_ERROR_PCT          0.05                            ///< Minimum ultrafilteration rate accuracy in percentage of set point (5%) over each hour of treatment.
 #define MAX_UF_ACCURACY_ERROR_ML                250.0                           ///< Maximum ultrafiltration accuracy error in mL over the entire treatment.
-#define UF_ACCURACY_CHECK_INTERVAL              ((1 * SEC_PER_MIN * MS_PER_SECOND) / TASK_GENERAL_INTERVAL)  ///< Ultrafiltration rate accuracy check interval count
+#define UF_ACCURACY_CHECK_INTERVAL              ((1 * MIN_PER_HOUR * SEC_PER_MIN * MS_PER_SECOND) / TASK_GENERAL_INTERVAL)  ///< Ultrafiltration rate accuracy check interval count
 
 // ********** private data **********
 
@@ -58,6 +60,7 @@
 static U32 setDialysateFlowRate;                        ///< Currently set dialysate flow rate (from prescription).
 static F32 maxUFVolumeML;                               ///< Currently set total ultrafiltration volume for treatment (from prescription).
 static F32 setUFRate;                                   ///< Currently set ultrafiltration rate (from prescription).
+static F32 maxUFRateAccuracyError_Ml_hr;                     ///< Minimum ultrafiltration rate accuracy over 1 hour duration (5% or 100 mL, whichever is greater).
 
 static U32 uFAccuracyCheckTimerCtr;                     ///< Timer counter to determine when next to check ultrafiltration accuracy.
 static F32 lastUFVolumeChecked;                         ///< Starting ultrafiltration volume for accuracy check.
@@ -107,6 +110,7 @@
     setDialysateFlowRate = 0;
     maxUFVolumeML = 0.0;
     setUFRate = 0.0;
+    maxUFRateAccuracyError_Ml_hr = MAX_UF_RATE_ACCURACY_ERROR_ML_HR;
 
     uFAccuracyCheckTimerCtr = 0;
     lastUFVolumeChecked = 0.0;
@@ -149,6 +153,8 @@
     setDialysateFlowRate = dPFlow;
     maxUFVolumeML = maxUFVol;
     setUFRate = uFRate;
+    maxUFRateAccuracyError_Ml_hr = MAX_UF_RATE_ACCURACY_ERROR_PCT * uFRate * (F32)MIN_PER_HOUR;
+    maxUFRateAccuracyError_Ml_hr = MAX( maxUFRateAccuracyError_Ml_hr, MAX_UF_RATE_ACCURACY_ERROR_ML_HR );
 
     if ( TREATMENT_DIALYSIS_STATE == getTreatmentState() )
     {
@@ -601,37 +607,46 @@
 /*********************************************************************//**
  * @brief
  * The checkUF function checks ultrafiltration accuracy for the last
- * minute and checks total UF volume.  Triggers an alarm if out of spec.
+ * hour and checks total UF volume.  Triggers an alarm if out of spec.
  * @details
  * Inputs : uFAccuracyCheckTimerCtr, lastUFVolumeChecked, measUFVolume
  * Outputs : uFAccuracyCheckTimerCtr, lastUFVolumeChecked
  * @return none
  *************************************************************************/
 static void checkUFAccuracyAndVolume( void )
 {
-    // check UF accuracy at 1 minute intervals
-    if ( ++uFAccuracyCheckTimerCtr >= UF_ACCURACY_CHECK_INTERVAL )
-    {
-        F32 uFMeasRate = measUFVolume - lastUFVolumeChecked;
+    F32 uFMeasRate = measUFVolume - lastUFVolumeChecked;
 
-        // check UF max rate
-        if ( uFMeasRate > MAX_UF_RATE_ML_PER_MIN )
-        {
+    // check max UF rate in last hour   // TODO - is this check necessary considering next check below is a tighter check on this?
+//    if ( uFMeasRate > MAX_UF_RATE_ML_PER_HOUR )
+//    {
+//#ifndef DISABLE_UF_ALARMS
+//        SET_ALARM_WITH_1_F32_DATA( ALARM_ID_UF_RATE_TOO_HIGH_ERROR, uFMeasRate );
+//#endif
+//    }
+
+    // check UF rate diff from target in last hour
+    if ( uFMeasRate > maxUFRateAccuracyError_Ml_hr )
+    {
 #ifndef DISABLE_UF_ALARMS
-            SET_ALARM_WITH_1_F32_DATA( ALARM_ID_UF_RATE_TOO_HIGH_ERROR, uFMeasRate );
+        SET_ALARM_WITH_1_F32_DATA( ALARM_ID_UF_RATE_TOO_HIGH_ERROR, uFMeasRate );
 #endif
+    }
+    // if actively performing ultrafiltration right now, increment timer and see if time to start another 1 hour check period
+    if ( ( DIALYSIS_UF_STATE == currentDialysisState ) && ( UF_RUNNING_STATE == currentUFState ) )
+    {
+        if ( ++uFAccuracyCheckTimerCtr >= UF_ACCURACY_CHECK_INTERVAL )
+        {
+            // reset for next check interval
+            lastUFVolumeChecked = measUFVolume;
+            uFAccuracyCheckTimerCtr = 0;
         }
-        // reset for next check
-        lastUFVolumeChecked = measUFVolume;
-        uFAccuracyCheckTimerCtr = 0;
     }
 
     // check total UF volume error
     if ( ( fabs( refUFVolume - measUFVolume ) ) >= (F32)MAX_UF_ACCURACY_ERROR_ML )
     {
-#ifndef DISABLE_UF_ALARMS
         SET_ALARM_WITH_2_F32_DATA( ALARM_ID_UF_VOLUME_ACCURACY_ERROR, refUFVolume, measUFVolume );
-#endif
     }
 }